How do I switch iTunes account on iPhone after troubleshooting failed?

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Switch itunes account on iphone after troubleshooting failed

I've signed out of iTunes and icloud twice, the second time I turned off the phone and waited a few moments before signing in to my iTunes account in both the apple id and icloud sign in pages. But I can't update my apps because the iTunes email it wants me to confirm is NOT MY EMAIL ADDRESS. it is my boyfriends, and we do share a computer, but I did not sync to his iTunes, I synced to mine. What is happening and how do I fix it?!?!?!?