How do I change the scaling options in AMD Catalyst Control Center?

Question

I've just switched out my old GTX 470 for a new ASUS Radeon R9 280X and now when I choose the resolution 1920 x 1080 it doesn't fit my 1920 x 1080 monitor. It just doesn't fill up the whole screen and leaves black bars around the image. I read that this can be because of the scaling options in AMD Catalyst Control Center, so I checked it out and noticed that my scaling-options are locked. I can't lower or raise the overscan to make the image fill out the whole monitor. Does anyone know what is causing this? Thanks in advance!