Norton won't let me change my autopay so I can use paypal credit

I imagine you’ll need to wait

fwiw: as far as I’m aware ~30+ days from term expiry - users report not able to change subscription status

Do you see Manage Licenses / Manage Renewal on your My Subscriptions page?
https://my.norton.com/extspa/account/subscriptions

Manage Renewal

Unsubscribe