2 iphones with same id

Just recently my friend came over to my house with his iphone. He wanted to get songs off of my mac so he took a bunch of songs but now when he goes to the itunes or iapps store on his phone my name comes up telling him to put in my password. Does anyone know how to fix this. Sorry if it's a dumb question but i am new to both the imac and iphone.

Until he syncs the phone with his iTunes library, it will continue doing that. The store on the iphone is linked to the account used on the iTunes library that it is synced with.

Thank you.