Removing parents card on Payment and Delivery and App Store when in an Apple Family

I have my own personal card, however I am in an Apple family and so whenever I try to make any in-app purchases, it automatically uses my parents card. My parents and I have tried to resolve the problem, however it says I must verify my mothers card (which it won’t let me do) and won’t let me add my own card or remove my parents. This is all happening in the payments and delivery section in settings and the App Store. My mother cannot find anything that will help me and I don’t have any restrictions set so I don’t understand why this is happening, especially because I can use my own card for Apple Pay when paying for things in stores. However I cannot leave the family as we have some joint subscriptions. Does anyone know how to fix this?