Adding new iTunes Account to iphone 4
I just bought my brother in laws iphone 4 and is linked to his itunes. I also have an itunes account. When I go to itunes on the iphone its asking for his password. How can I delete his account info and add mine to log in to my account. I was told to do a factory reset, This phone is jailbroken and hate to loose any apps and other items. Is there a way to delete his account and add mine. Thank you in advance. Eddie