If you happen to use Mod Organizer, you might have to check whether it stored MO specific .inis somewhere that it loads instead of the actual .ini in your documents folder. That tool does some seriously weird shit in regard to file access redirection without really explaining any of that.
Starting the Skyrim launcher from MO and changing the res there might also help in that case.
General hint: you can comfortably revert changes vorpX does to game .ini files in the vorpX config app. No need to search for the backup files on your PC manually.