1. Open PyCharm and go to File > Settings (or press Ctrl + Alt + S).
2. In the Settings window, navigate to the Project > Project Interpreter section on the left side.
3. In the Project Interpreter section, you will see the current Python version being used by your project. To change the Python version, click on the drop-down menu next to the current version and select the desired version.
4. If the desired version is not listed in the drop-down menu, you can click the gear icon next to the menu and select "Add Local". This will allow you to select a local Python interpreter on your machine.
5. Once you have selected the desired Python version, click "Apply" and then "OK" to save the changes. PyCharm will now use the selected Python version for your project.