The Customer History report will show all items that the customer has ever ordered, including all the payments the customer has made. You have a grand total of outstanding balances.
To print or view a Customer's History, click Order Entry: Reports: Customer History. A "Customer History" form will appear. Enter the customer's phone number and click OK. The screen will revile all sales in order sequence with a subtotal for each open order. There is a Print Button if you want a hard copy to send to the customer. Otherwise, click Menu to exit out.