Answer:
When you get the skull on any level (to pick it up get close to it and hold X thats if u have it for xbox) a flash of white light will appear on you and dont panick its normal.If you search up what the skulls do u will be able to do that.to use it on another level save and quit then u can use it on that level.Once u turn off whatever u have the skull abilites will disappear so dont panick its normal.