Select Accounts Receivable Main menu > Invoice Data Entry.
In the Invoice Data Entry window, at the Invoice No. field, enter the existing invoice or credit memo number to adjust. For more information, see Invoice Data Entry - Fields.
At the Customer No. field, enter the customer number for the original invoice or credit memo.
The ""Invoice already exists. Would you like to adjust?"" message dialog box appears. Click Yes.
You can accept or change the invoice date displayed. Change any header information, as necessary