Apply Existing Credit, Where for Deposit?

I am moving from a free accounting solution to Quickbooks for Mac Desktop. In setting it up, I am recording all invoices and payments from the current year. I have a client who I managed to somehow (I don't remember how, it wasn't via a credit memo as none exist) give an existing credit of $256, which is correct. The payment was via a check deposited to my bank's checking account. I now want to apply that credit to an invoice, which I figured out how to do. The part I'm unsure of is with the Deposit section... I don't think I want to deposit the existing credit to the bank's checking account, because the check that the credit applies to was already recorded. I don't understand the software and accounting principles well enough to know how to do it correctly.

EDIT: I figured out how I got the credit... I overpaid an invoice and didn't apply the overpayment to another invoice. The overpayment then did not get deposited to my bank's checking account. I need to set the deposit to the bank's checking account.