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Print [Python] seen as a keyword in Pycharm

I'm using Pycharm (2019.1.2 x64) from quite a while and I never changed the standard settings.
The standard settings diplay keywords (def, class, if) in orange, pressing tab will auto complete the keyword and add a space, build-in functions (sum(), map(), print()) are displayed in purple and pressing tab will auto complete the function name, add brackets and move the cursor inside the brackets.
This is the desired behavior and it's what I get when opening any project in Pycharm except one.
In a single project this behavior suddently changed, I did nothing but writing and running code.
I noticed because tab suddently started indenting by 8 spaces instead of 4, no big deal I changed it back to 4 in the bottom of the IDE, but I also noticed that print was seen as a keyword (so orange with no brackets) instead as a built-in function, just like in Python2 (I never used it and the project's interpreter was Python 3.7). from __future__ import print_function would turn print into a function again but it's Python2 stuff.
I fixed it by creating a new virtual environment and setting up the interpreter again, so my question is:
What causes this unexpected behavior?
I would like to avoid this when working on my most "serious" projects. Thanks all.

NEW ANSWER
Well, this happened to me just yesterday while I was working on my tkinter project. It showed tkinter in from tkinter import * "Module not supported in Python 2.7", even though I was using Python 3.8.
Solution One
To fix this issue, I just simply went to
File > Settings > Appearance and Behavior > System Settings > Updates
And updated PyCharm to the latest one. It worked for me.
Solution Two
Another method I found out is to go to
Press Shift Key Twice > Typing "Restore Default Settings"
Doing this will also restore all the settings partially and fixes the problem for me.
Why Did This Happen?
This is due to a bug in older versions of PyCharm (probably). I got this bug while testing some Google API that was in Python 2.7. If you ever opened a project containing Python 2.7 Interpreter and opened another project that is in Python 3 and above, PyCharm thinks that the code that is written is in Python 2.7 and just formats the guide according to it. Some example can be "f" in print(f"{some_variable_here}") being shown as "Not Supported In Python 2.7". This is just my theory I may be completely wrong here.
OLD ANSWER
Are You Using macOS? if yes, macOS comes with Python 2 preinstalled. So probably this may be a bug. I suggest going to the bottom right corner and there would be written "Python (Version)". If it is something other than 3 or above (like 2), click on it, and go to "Interpreter Settings" and there, from the drop down menu, select the other Python interpreter that is installed on your device.
If this does not work, then it may be a theme bug, or something to do with PyCharm itself (probably). Reinstalling and clearing the cache should probably work.

python power shell issues

Edited to include a specific example
I am learning to use python and work in a windows 10 environment (although on 3 separate computers). I have gotten past the "add python to %PATH% issue" but continue to see odd outcomes when I call simple scripts from powershell compared to running them from the python terminal. For example, I often see that lines of code are duplicated, even simple print statements. A second repeating issue is that some (but not all) modules work fine in the python terminal but can't be found when running a script from powershell, despite using pip install within powershell to install it in the first place.
Rather then seeking help on a specific issue, I'm hoping for some guidance into how powershell and python interact that might help me understand or identify some commonalities in these issues I keep experiencing that are common from within powershell. If thats as simple as redirecting me towards another source even that'd be apprecaited. But my search results always turn up the common issue of powershell not knowing what python is, and needing to add python to the PATH. But as indicated, I have already gotten past this and can get %50 of my python to work from powershell. There must be something else perhaps obvious to others that I'm missing that can help me understand why some things aren't working while others are.
Thanks for taking the time to consider my problem and any advice is greatly apprecaited.
Here is an example from some code I am trying to get working, but in troubleshooting I have taken out a lot of code and am now only running what is shown that defines a dataframe and a print statement. Everything works line by line in python, but when I call the script from powershell, the print statement executes twice.
#!/usr/bin/python3
import pandas as pd
joedata = {'fpr': [0.2,0.4,0.8], 'tpr':[0.9,0.5,0.1]}
joeframe = pd.DataFrame(data=joedata)
print(joeframe)

Concerning modules, you probably have multiple versions of Python installed on your system. Calling pip in the Powershell doesn't mean that it will install for the Python installation which is called by default when you execute Python in the Powershell. So you should try to figure out on which version pip is installing packages and which version is actually used when executing a script.
EDIT: I tested the example that you gave in Powershell and I don't have the problem, it's working fine.
Moreover, for me, without doing any special configuration, in Powershell the commands pip and python refer to the same version of Python. If by default everything is ok, you should consider uninstalling Python and just running the installer again and let it manage the PATH, etc.

Nuke Accessing Wrong Version of Python

I am experiencing a very similar problem to this one:
Using multiple versions of Python
The context of my problem though I believe is different enough to warrant a separate question. I receive this error when trying to launch the non-commercial version of The Foundry's Nuke. The error manifests similarly to this:
http://community.thefoundry.co.uk/discussion/topic.aspx?f=197&t=113695
,except the error message returned before the command prompt immediately closes is that displayed in the first link. This leads me to believe that Nuke is trying to access the wrong version of Python (currently it is trying to access
Python 3.5).
Assuming my line of thinking is correct, how can I change the version of Python that Nuke is attempting to access? None of the advice in the Foundry forum link proved successful either, I should mention. And according to what I have read,the latest version of Python to be used by Nuke is 2.7. So to ask the question more specifically, how can I make Nuke access Python 2.7 as opposed to Python 3.5? Both are installed on my desktop, 64-bit Windows 10.
The syntax error returned as the prompt closes and Nuke fails to launch

I have removed PYTHONPATH from System variables and Nuke9.0v8 non-commercial now appears to function properly. As this has not caused any problems with other applications and programs that rely upon Python 2.7 or 3.x, I believe this solution was sufficient in solving the problem I initially proposed. Previously I had specified the location of Python 3 within the Path variable, and this I have NOT modified. I imagine that this solution should be applicable to any software that generates the error message linked in the question.

Sublime Text 3 Output Python

I work on two computers, I have Sublime Text 3 and Python 2.7 on both of them.
Recently, without changing any configuration (except maybe installing some packages like ANACONDA for ST3), when I build my python code on Sublime Text 3: e.g.,
print 'Hello world'
Console output is just showing:
[Finished in 0.1s]
And nothing more, (I want to see the printed text), this is quite irritating because for the life of me I can't figure out how to solve this.
A related and perhaps identical problem is experienced by #Jens_Leersen.
I've tried the answer contained in #radioxoma 's answer but to no avail.
Related example

I got that thing as well. You can change it by Tools/Build with and choose "Python" instead of "Python- Syntax Check". It turns out that I clicked "Syntax Check" the first time I try to compile. My dumb mistake costs me a few minutes of panic.

This got fixed by uninstalling python 2.7, and installing Anaconda with python 3.5, then installing anaconda through Package Control.

Use Ctrl+shift+b this will show a box asking you if you want to use Python or Python Syntax Check. Select Python and once you are done you will be able to use Ctrl+b to build you code and see the output at the bottom. this answer is just about the same as #1757 answers right below i am just using shortcuts to get to the same functionality
Thank you #1757

Its simple, press ctrl + shift + b and click on python (not python - syntax check).
Build and Voila!

Need Python guide on Windows

I am trying to set up Python on Windows 7. I haven't used this language before so it seems strange to me.
I've downloaded lastest Python release 3.2.2 from official site and upadate path variable.
However I still can't even run simplest program ever like this :
print 'Hello, world!'
It says that there is a syntax error and the last character ' is highlighted with red.
I don't know if my path variable has been set properly. Here is where I installed Python :
C:\Software\Python32
So I added such a variable : var name = PYTHONPATH , var value = C:\Software\Python32\Lib
Is there something with auto-completion and with errors/warnings details ( which line, hint what can be wrong ), for example like Eclipse or NetBeans OR should I use this installed Python IDLE GUI for delevoping or stuff like NotePad++ ?
Actually what is this Python shell for ? - I know that I can type in some arithmetic operations here and I will get results, but is it used for something more advanced ? ( Is it used when I am writting something bigger ? )
Could someone describe simple way to write and execute a program ( or script I a total beginner so I don't really know what it is going on here ) ?

In Python 3.2 you have to use print in the below manner. The parentheses are mandatory. (print became a function in Python 3)
print('Hello World')

As Venk stated, the print statement in Python 2.x has been replaced with print() in 3.x, so your statement should read
print('Hello World')
Since you're new, here some things you should know about Python versions:
Python currently comes in two flavors: Python 2.x and Python 3.x.
Python 2.x has been in development since the late '90s, so most existing codebases, frameworks, and libraries are written in this flavor of Python. Each successive version is backwards compatible, so, for example, all code written in Python 2.4 can be run with Python 2.4+. Its current revision is 2.7.2, which was released last year.
Python 3.x is considered the "future" of Python, and purposefully breaks a lot of the conventions, such as the print statement, in favor of a clearer, more explicit language. Most libraries are working to port over to Python 3.x, but since there are extensive changes in the structure of the language, most library maintainers have not yet been able to release a Python 3.x compatible version with the full features of the Python 2.x version of the library.
If you're developing now, you should learn Python 2.x; otherwise, it's recommended you learn Python 3.x.
To answer your other questions:
Python's native IDLE is an excellent IDE, but if you're looking for something more advanced, you may want to try out Eclipse's PyDev extension or PyCharm. I personally prefer PyCharm, since it doesn't keep giving me errors when I'm importing/using nonstandard Python libraries/frameworks.
In addition, Python's shell is used to interpret Python scripts (in the background) and for interactive interpreting (i.e., quick and dirty testing), and can execute code you type into it. The latter, however, is not recommended, as a single syntax error in multiple lines of code can force you to retype all the lines to fix a single bug.
Furthermore, all Python scripts end in .py, so if you can see the file extensions, you can convert a text file into a Python script, and run from shell by typing python path/to/file.py. Note, however, that you still have to write a valid Python script, or it will not run.

I suggest A Byte of Python. It'll take you through install, REPL, syntax, and the std library.

The python shell is for entering code interactively.
Try the following: http://docs.python.org/tutorial/

I've been using Python on Windows 7 for 3 years now, and I strongly recommend Notepad++ as your editor/interpreter. It is ideal for people who want to play around with the language and are learning. Notepad++ can be customized for almost any language and is free for Windows. Follow this link
and take a look at how to conveniently use Notepad++ to execute Python scripts.