I am trying to change my address on the W-9 Form Section, as the wrong address appears on upwork, but it seems to be logged in.
I think this is a system bug.
How do I go about this?
You should be able to update the address. Can you please go to Settings > Tax Information and click on the edit icon as shown in this screenshot? After that, you should see a 'Change' link in the Address section from where you can make further changes to your address. Let us know if you need further assistance.