Allow me to assist you in categorizing the downloaded bank transactions.
QuickBooks Desktop for Mac remembers the last selected account when categorizing the downloaded bank transactions. For example, if the name of the last account used for Safeway Grocery's transactions is Groceries, then it'll automatically appear in the Account column.
This is the reason why it's not yet working on the newly added credit card account. However, the next time you're categorizing the transactions on this account, you can be certain that the last selected accounts will also reflect.
I added this link if you need help in creating or editing a renaming rule for payee names: Manage renaming rules for payee names in QuickBooks Desktop for Mac.
Comment again here if you need more assistance in handling bank transactions. Stay safe!