I need to change the bank for my plan, not finding how

Hello embquilt,

We have a great support article that might help with this. Please take a look at it here: If you need to change or update your Apple ID payment method - Apple Support. Follow this guidance:

"Update your payment method on your iPhone or iPad

1. Open the Settings app.
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.
4. Tap Add Payment Method, enter the new payment method, then tap Done.
5. Tap Edit.
6. Tap the red delete button next to the old payment method, then tap Delete."

We hope this helps. Let us know if we can assist with anything else at all. Take care.