I decided to get crazy, so I clicked on Apply credits, clicked on the invoice to have it applied to, clicked Deposit To to be my checking account, clicked Save, and everything worked as I'd hoped. The credit was applied to the invoice and there was not a deposit entry entered into my checking account. I did this for several similar transactions and never received a deposit into my checking account. Let me be clear, I had left the Amount field at zero because there wasn't any additional incoming money, just the use of credits. It would be nice if this was somehow indicated through QB either on-screen or through documentation, but I wasn't able to find anything that made this clear.