Hello, and sorry you're having problems. To update your Kindle payment information, this cannot be done on the Kindle itself- you would need to log onto Amazon.com from a Laptop or PC and then change the "One click settings" as shown below:
Manage Your Kindle Payment Settings
You can view or edit your 1-Click payment method by visiting the Settings page within Manage Your Content and Devices.
To view or edit your 1-Click payment method:
Go to Manage Your Content and Devices. From Settings, select Edit Payment Method below Digital Payment Settings. Select the desired credit card information, or add a new card, and then click Continue. Enter the desired billing address, and then click Continue. You will be taken back to the Digital Payment Settings page where you can view your edited 1-Click payment method.
If you need further assistance let me know. Please do not forget to click a POSITIVE RATING before you go- as it's how I am credited for my work. You can follow up at any time, at no additional cost.