Your payment method was declined.please enter valid payment information couldn't change my store also hence that due amount so pl

Hi

Follow the instructions here, including checking that your address details fully match those on file with your card issuer / bank:

• Change or remove your Apple ID payment information - Apple Support
• Payment methods you can use in the iTunes Store, App Store, and iBooks Store - Apple Support

You may also wish to check with your bank, in case it declined Apple's payment authorisation request.

If you still need help, contact iTunes Support:

Contact - Official Apple Support

You can only use a credit card from the same country listed as your country with the iTunes Store.

Some countries do not allow payment with debit cards, it must be a credit card.