If payment method can't be added or changed

Check the following

1. The payment method that you are adding is of the same country as that of App Store Country on your iPhone
2. You have valid payment plan / debit / credit card from an authorised bank from the same country
3. Payment methods that you can use with your Apple ID - Apple Support
4. If you're using Family Sharing, only the family organizer can update the payment information. Learn more about payment information and Family Sharing.

If you can't choose None when you edit your Apple ID payment information

1. If you have an unpaid balance or payment due
2. If you have a subscription that automatically renews
3. If you're using the iTunes Store or App Store for the first time
4. If you are not in the country or region you’re creating an Apple ID for
5. If you changed your country or region
6. If you're a part of Family Sharing