To use a different credit card:
You can change your credit card number from the Account page without canceling the subscription.
To use a different payment method:
*When there are some days left in the subscription period, the restart option will not be shown. Please wait until the subscription period expires then restart your account with the payment method you of your choice.
*You cannot change it to iTunes Store Payment. iTunes Store payment can be selected when you sign up from iPhone/iPad/iPod touch/Apple TV or restarting your account signed up with iTunes Store payment.
*When it says ”Forbidden,” please switch to the owner profile.