Changing the Billing Information in the new Rakuten TV app is very easy.
Click on the symbol as in the picture:
Go to "Settings"
From "Settings" you can update your payment details.
For older TV models, You will find "Settings" by clicking on "Menu" at the bottom right corner of the app.
1. With the red button of your remote control go to Menu.
2. Go to Settings.
3. Pair your account (in case it is not paired yet).
4. Click on Update payment details:
5. Enter your Credit Card number and click Next.
6. Enter the expiration date and click Next.
7. Enter the 3 digits of the CVV and click Next.
8. In order to confirm the information click on Press OK to continue.