i want to pay for subscriptions with my apple cash balance

Set your Apple Cash as the default payment for your Apple ID - Change, add, or remove Apple ID payment methods

How to change your payment method on your iPhone, iPad, or iPod touch

1. Open the Settings app. 
2. Tap your name.
3. Tap Payment & Shipping. You might be asked to sign in with your Apple ID.

• • To add a payment method, tap Add Payment Method. 
  • To update a payment method, tap the payment method, then edit your information. You might need to enter the security code that's printed on your credit or debit card. If you see Apple Pay after the last 4 digits of the card number, go to the Wallet app to edit the card information.
  • To remove a payment method, tap Edit, then tap the Delete button. 
  • To change the order of your payment methods, tap Edit, then use the move order icon .*