can't change the PayPal payment option

Change or remove your payment information from your iTunes Store account (Apple ID) - https://support.apple.com/HT201266 - "On your iPhone, iPad, or iPod touch, you can change the payment information for your Apple ID in Settings. On your Mac or PC, you can change your payment information from the iTunes Store." - More information at: https://discussions.apple.com/thread/3251676?answerId=15891166022#15891166022

Do you have anything such as an automatically renewing subscription which may be preventing this?

iTunes Support Contact - https://www.apple.com/emea/support/itunes/contact.html

When I try to do that on my new iPad mini, it pops this up and won't let me change it:

PAYMENT TYPE

PayPal is not supported on this device. To manage or change your payment method, go to the iTunes Store on your computer.

You must verify your payment info before you can make purchases.

How do I change the method on my iPad mini?

Of course, this happens because I am trying to install a free app...

The edit payment option is not there on any of my devices or my account information page with my Apple ID.