Changing payment method for Family sharing?
Apple has stored an old, dead credit card number in my account for "Family sharing". I have, I think, tried everywhere to edit this so the card number is up to date, but I can find nowhere that provides an option to change the payment method associated with "Family sharing". My AppleID has all the right card numbers, but both in that pane on my desktop System Preferences and also on the relevant places in the App store the wrong number is shown for Family Sharing and is impossible to edit. I'm sure I'm missing something obvious, but how can I fix this?
Mac mini, macOS 10.12