I just received the new card today - guess now I need to cancel the old United card...

Question if anyone knows. I went and linked the new card to our UA an CO accounts and made it the primary card. One of the things I read said to "link the card to your reservation." We have award flights coming up in May - and looking at everything I could see, there wasn't a place to link a credit card.

Did I miss something, can it even be done, does it matter?