UserGameSettings information

So I followed this tutorial to implement Video options saving and loading :
https://impetus-games.com/blog/Persistent-Graphics-Settings-in-UE4

Unfortunately, my implementation seems to work 50/50 and the documentation regarding this feature is pretty limited.

For instance, which UserGameSettings file is modified when in the editor ? Standalone ? Build ?

I have read this file’s content gets edited only when it is different from the default one, is this the case ?

I’m having a bit of trouble trying to find why I’m having the problem that I’m having and help would be much appreciated. Thanks !