Set default payment

See -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

• If you want to change your card, add first the new card, then remove the old one.
• or if you use your Apple ID balance, set your Apple ID balance as your default payment.

Have you read this -> Add a payment method to your Apple ID

Add a payment method to your Apple ID – Apple Support (UK)

Get more help and assistant from Apple directly, see Contact Apple for support and service -> Contact Apple for support and service – Apple Support (UK) 

I had no choice other than contact with support.

So I use Apple ID balance.

How to make it default payment method?

Same answer, see my previous post:

• if you use your Apple ID balance, set your Apple ID balance as your default payment.

I don't see this option