How To Override Quickslot hotkeys?

Hey guys. When I say quickslot hotkeys, I mean on the bottom right of your screen, Shift Control Insert Selete Home Page Up Page Down End 8 square box. I think I remember I used to be able to accidentally put a seperate key on it, like x, in that hotkey square. Does anyone know exactly to override one of those keys?

The reason being is that I want to see when one of my skills cools down, but I don't want to put it on one of those specific keys I mentioned.

Thanks.