IN Halo 3 how can the skulls turn off.?

[Lil Ay]

I am stuck at a part in campain in legendary and i found 2 skulls that can help but how can u turn off the skulls when you are done with them? Do they turn off by themselves?

 

[Shikamaru]

You have to leave the game, then in the menu for the campaign go back to the skulls menu and turn them off. They don't turn off or on by themselves, you have to do it all.