This app?
https://nvidia-inspector.en.softonic.com/
When you make changes are you sure that you are saving/confirming those changes in some manner?
Some button that is a "Save". a "Yes", or an "Ok"? "Approve"?
You may need to scroll down some to find or see the confirmation.
Another thought is to double check the changes you make. If not supported by hardware, etc. the changes may simply be reverting to the default values.