Had to set a different resolution, to find one that allowed custom settings. Then I set my setting of choice.
After that, I set it back to 1680 x 1050 (my native resolution). The option became greyed out againg and back to the default setting. But when I change the resolution to anything other than the native resolution, it uses the custom setting set by me.
I guess that is how they set it up to work. I find it just overly complicates a general setting. They should drop that greyed out at native resolution because it don't sclae bit. No point :|
I hope that is clear.