To
apply a credit memo agains an Invoice go to the Invoices screen and click on an
existing Credit Memo/PrePayment.

The
payments screen will open with the pre-payment information already populated in
the fields.
Choose from the drop down menu the Invoice/s the Deposit/Pre-Payment
will apply to and Click the Save/Print options to apply the Deposit/Pre-Payment
to an Invoice.

The
results will appear just like an Invoice with a payment applied. Any additional
balance will appear in the top field in the invoices screen and in the P/D
Balance column.
