How to change key in garage band

Hi all...I've never ever used garage band before, so I'm really lost. I want to import a karaoke tune from itunes over to garage band and change the key. I've managed to drag the tune into garage band and created a new project. now i'd like to change the original key. do i just click on the key in the little blue bar at the bottom and save as? secondly, how do i stop the drum from playing? i've muted it, but i'm just wondering why that instrument keeps getting highlighted and amplified when i open garage band. thanks very much all. i hope i make sense.