Unable to type in credit card # to update my iCloud

Hi Gr8Apple4me

welcome to the Apple (user-to-user) Community.

Re: "Unable to type in credit card# to update my iCloud payment info"

Your Apple ID is the account you use to access Apple services, like the App Store, Apple Music, iCloud, iMessage, FaceTime, and more. 

How to change an Apple ID payment method:

What to do: If you need to change or update your Apple ID payment method – Apple Support

Else:

You may need to add a new card, before you can delete an old one:

How to Add an Apple ID Payment method:

Add a payment method to your Apple ID - Apple Support

How to delete an Apple ID payment method:

Remove a payment method from your Apple ID - Apple Support

Trouble-shooting if needed: Check which payment methods Apple can accept in your country or region:

Payment methods that you can use with your Apple ID – Apple Support

All the best :-)