Change the credit card shared by a Family Sharing group on Mac
If you’re the family organizer, you can change the default credit card used for purchases and subscriptions by all family members in your Family Sharing group.
In the App Store
on your Mac, click [your name] at the bottom of the sidebar.If you don’t see your name, click Sign In and follow the onscreen instructions. See Sign in to the App Store.
Click Account Settings on the right, then enter your Apple ID and password if prompted.
Below Apple ID Summary, click Manage Payments next to Payment Information.
Do any of the following:
Change the default payment method: Click the Sort icon next to a payment method to change its position in the list. The first payment method in the list is the default method used for Family Sharing purchases and subscriptions.
Add another payment method: Click Add Payment and follow the onscreen instructions.
For information about changing your Family Sharing payment method in Apple Music, see Set up and view an iTunes Store account in Music.