Could you please elaborate on what specifically is not working? So that I may better assist and help you. But just to confirm:
1) To unlock cheats, you must hold the [interact] button (default is space bar) for 5 seconds while in the pause screen.
2) After the cheat screen has been unlocked, the shortcut buttons will work, and you can change them inside the cheat window.
3) You should also make the cheat screen permanently unlocked, by going to: options -> advanced -> permanent cheats ON