Hello, To update your Amazon one click payment, you would need to log onto www.amazon.com from a PC or laptop- you can't do it directly on your Kindle.
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:
If you need further assistance let me know. Please do not forget to click the 5 STAR RATING, at the top of the page for my efforts. It is my livelihood and you can follow up at any time if needed.