Cannot edit payment method

I am trying to edit my payment methods for my apple account. I go into settings, tap my name and go to payment and shipping. My one payment method is listed (PayPal) but if I click on it, nothing happens. There is no button to add a new payment method and the edit button is grey so I cannot click on that either. The only thing I can access is my shipping method.

how can I add a different payment method?