Delete trainer and all files in
Learn how to make your own Trainer Cleaner for the above paths Here. Link
Reboot PC to clear excess memory, get a fresh copy of latest trainer and extract it. Run trainer as admin, read the instructions and try again. At times, a new game may be needed to resolve failed options if the data in your save file was altered. Use on a new game and test the option. If it now works, quit to main menu and load your save and try it again. May also need to run the game without the trainer first and play a bit so the save file gets updated to use possible new values.
Deleting the files should be sufficient, no need to get a new trainer unless it was updated since last download.
This would probably be the easier solution than a full resource editor.
Did the game have a patch? If not, see my above post for clearing the work folders.