@AmericanRV 

"2. I create a deposit, and leave the "Deposit To" as my default checking account. Rec'd from: Vendor name. From acct: Accts payable. Memo: A note on what it's for, Pmt Method: Check, amount, and save."

Stop right there.  After this step, you're done as far as the deposit is concerned.  Finished.  Finito.  Done like dinner.  Moving on.  Look at your bank register, you will see the deposit listed.  You're getting tripped up by the credit memo and $0.00 check.  The credit memo and the $0.00 check have nothing at all to do with the deposit.  That is just how QB records the offsetting account (reason) for the deposit and gets it listed under the vendor' account.