When a household has an existing credit (due to a prepayment, cancellation, withdrawal, etc.) you may use that to pay for items in the shopping cart.
Add items to the shopping cart as necessary. Click the Payment as normal.
The total amount for the item(s) will show WITHOUT the credit. Applying the credit will happen once you arrive to the Global Sales Payment screen.
The credit will automatically apply once you've reached the Global Sales Payment Screen. Select your Pay Code to make payment for the remaining balance and then click Process to complete the transaction.
If the credit on the account is large enough to pay for all items, all you will need to do is click the green Process button.