How to Change an Account in an App Store
The iTunes App Store offers over a million applications for productivity, lifestyle, entertainment, games and educational purposes. When you set up your App Store account and enter your credit card information, the data is permanently stored so that when you download an app you do not need to enter payment details every time. However, you may wish to change your account information, or the account itself, at some point. Editing and changing your App Store account information is a simple process done in iTunes.
Launch iTunes and go to "Store" in the toolbar, then select "View My Account." Enter your iTunes password and select "View Account."
Click "Edit Account Info" to change your username, password and privacy settings. Click "Edit Payment Information" to change the account your purchases are charged to.
Change your account entirely by creating a new account if you wish. Go to "Store" and click "Sign Out," then return to "Store" and click "Settings." Click "Create New Account." Enter an email address for your Apple ID and a password, then enter your billing information. Click "Next," then click "Done" to complete the process.