Both Game.ini and GameUserSettings.ini are located in,
Filepath may differ a bit.
On dedicated rented servers, the file path can differ quite a bit. Generally, they can both be found at a similar location like this(Nitrado),
Remember to exit your singleplayer game and your server before editing these!
In some cases, single-player ini’s can have permission problems, they can be set to read-only, or your game overwrites the ini after you’ve started it. Check file permissions if your changes won’t work.