you can change your payment information from the account information page on iPhone, iPad, iPod touch, Mac or PC. When you change your credit card number or billing address through the iTunes Store, your information on iCloud, Apple Store online store, iPhoto and Aperture will also be updated.

change payment information on iPhone, iPad or iPod touch

tap settings on the home screen.

tap iTunes Store and App Store.

tap your Apple ID. (You may need to log in with an Apple ID. )

tap view Apple ID.

tap payment information.

change your information, then tap done.

after changing your payment information, the iTunes Store will set an authorization retention on your credit card.