can someone help me with changing my payment method for my Apple Watch SE

What do you mean Payment Method for your Apple Watch SE? Apple Watches have no payment methods of their own.

They either use payment methods added to your Apple ID as shown in the support document you came from, or they use payment methods added to the Wallet App on the paired iPhone. Link-> Set up Apple Pay on Apple Watch - Apple Support

What exactly are you trying to accomplish?

Hello!

This article will help you update cards in Apple Pay on your Apple Watch:

Set up Apple Pay on Apple Watch - Apple Support

Regards,

Jakub