There are few methods of recording opening balances for Accounts Receivable account. Opening Balances can be entering via Customer Profile, General Journal or Invoices.
One of the easier methods of recording the opening balances for Accounts Receivable is to enter into the opening balance field of the customer profile. However, this is not the best method.
If you are in a rush, entering the opening balances via the customer profile is one of the solution, but this method does not break down the amount owe into the respective invoice. Example: if ABC Company has five outstanding invoices with the total amount due of twenty thousand dollars, you can only enter twenty thousand in the opening balance field. In this way, you have to manually track the invoice paid in the following month.
Another common method, which accountant likes to use is via general journal. That is, debiting Accounts Receivable account (need to select customer name at the name column field) and crediting Opening Balance Equity account. This method gives a clearer picture of the amount due per invoice (one invoice, one journal). However, this method doesn't give a nice presentation in Statement. In the Statement, the opening balances will shows as a general journal type instead of invoice or credit memo type of transaction.
A better method, which I preferred to use, is via Invoice (or Adjustment Note) transaction. First, I create a new item, which can be either an Other Charge or Service item, with the item name as Opening Balance and associate this item to the Opening Balance Equity account. In the Invoice entry, I will use this Opening Balance item and enter the amount due in the amount field of the invoice. This method is good, as it tracks the individual invoice owed with the original invoice date and invoice reference number, so it can age the invoice according to the invoice date instead of the opening date of your account. Besides, this method will show as invoice type in the statement of account.
Depend on your accounting requirement; select a method that meets your operation need.