If the Expense tool does not automatically link a transaction with a credit card in your profile, you see the message:
Click the icon to open the credit card selection screen.
If there is no matching card in your profile, you see a screen with an Add button:
Click Add to add a card to your profile (see Adding a Credit Card to Your Profile).
Once a card is added to your profile, clicking the icon displays the selection screen with a Choose button.
On this screen:
Choose an existing card in your profile from the list.
If you want to associate all transactions in your Expenses Wallet with the card number displayed, select the Assign this payment method… box.
Click Choose to associate the transaction with the card displayed.