You can easily switch versions from the Python versions submenu (below) accessible from the Run menu, the application toolbar and the Python interpreter submenu.
Registered python versions are automatically detected and listed and you can add unregistered Python versions using the Setup Python dialog box:
You can add new versions by selecting the directory in which they are installed. You can test, show in File Explorer and open a command prompt on existing python installations. Virtual envrironments (both virtualenv and venv) and conda installations are supported and work out-of-the-box. The python configurations are persisted, so you can pick your work in PyScripter next time you use it from where you left it.