I am not able to update my payment methods on iPhone 7plus

Hi there sangay30,

To update your payment method, you'll want to start by adding it as a new payment method, then remove your previous payment method afterwards. You can do so with these steps:

Add a payment method on your iPhone or iPad

1. Open the Settings app.

2. Tap your name.

3. Tap Media & Purchases, then tap View Account. You might be asked to sign in with your Apple ID.

4. Tap Manage Payments.

5. Tap Add Payment Method.

 6. Enter the payment method details, then tap Done.

You'll find this information here: Add a payment method to your Apple ID

Take care.

Ghj