How to Change the Payment Method in App Store?
If you change your payment method, make sure that your account information matches the credit card information on file with your financial institution.
Step1: Open the App Store of your iPhone, find and click iTunes & App Store.
Step2: Click your Apple ID→View Apple ID, and you need to sigh in.
Step3: Click Payment Information. If you’re using Family Sharing, only your family organizer can update the payment information.
Step4: Change or remove your information. To remove your payment method, you need to choose None. If you can’t find or select None, please call Apple Center.
Step5: Click Done, if you change the payment method to a credit card, the iTunes Store places a temporary authorization hold on your credit card to verity your updated account information.