pycharm convert tabs to spaces automatically

For selections, you can also convert the selection using the "To spaces" function. I usually just use it via the ctrl-shift-A then find "To Spaces" from there.

Change the code style to use spaces instead of tabs:

Then select a folder you want to convert in the Project View and use Code | Reformat Code.

This only converts the tabs without changing anything else:

Edit -> Convert Indents -> To Spaces