If a credit was created for a customer, and there were no open invoices to apply the credit at the time of creation, you may manually apply credits to customer invoices when a new invoice is saved.
To apply a credit, you must first open the customer record.
From the main menu, arrive at the Customers list with this path: Accounts Receivable> Customers.
The Customers list will be displayed. Locate the customer in the list, and then click on the hyperlink in the Customer # column to open the customer record.
The Customer record will be displayed. Click on the Credits tab. A list of all credits for the customer will be shown in the grid area. For the credit you want to apply, click on the Apply button on the credit in the grid.
The Apply Credit page will be displayed. If there are invoices with a balance greater than zero, they will be listed in the grid.
In the Apply column, type in the amount of the credit you want to apply to the invoice. You may apply the credit to multiple invoices as long as you do not exceed the amount of the credit.
When finished, click the Apply Credits button at the upper right of the page.