Hi again: I am going to assume that you want to get the NSF amount showing back onto the Customer's Accounts Receivable account and show the credit in the Bank account to record the NSF returned cheque. To do this I would go to the Sales window, choose the Customer, and instead of an Invoice# type in Returned Cheque and proceed to enter the amount (in total) and choose the account to credit as the Bank account number (instead of the usual Sales). Check the journal entry before you post it. It should be showing as a Dr. to Accounts Receivable and a Cr. to Bank. There is no need to back date it. The date you use should be the date of the notification that the cheque was returned NSF.
You will then have the amount back onto the Customer's account showing as receivable still. Rita