PyCharm 22.3.2 Professional version
To add PYTHONPATH to your current project
File -> Settings -> Project -> Python Interpreter -> in the drop down menu click Show All... -> click the tree-like icon -> + your PYTHONPATH
or
lower right corner click your current python interpreter -> Interpreter Settings -> in the drop down menu click Show All... -> click the tree-like icon -> + your PYTHONPATH
Then re-start PyCharm you should all set