Maybe this belongs in the applications department, but the My Account app is unique to T-Mobile android phones, since it was written by T-Mobile, so this seems a better place to ask. Normally I pay my monthly bill with this app. It always works fine. It would continue to work fine except I closed the bank account that I used to use and now have a different debit card. The app helpfully remembers the old card number since that is the card number I used last time. There are windows to enter security codes, phone number, etc., but I can't find any way to add or change a card number. Surely I am not the first customer in the history of T-Mobile to change banks. How in the heck do I change the debit card number?