@SQM
Did you have a liability setup for your mortgage payment?
The entry should be to Debit Mortgage Payable and Interest Expense, and the other side should be to credit the cash account used to pay the mortgage. If you did have that correct setup, then the entry to book the returned mortgage payment should be the opposite entry (Credit payable/Interest and Debit Cash).
Did you journalize your payment to the mortgage prior to making the entry to clear the mortgage?
The answer will assist in next steps.
