A customer made a payment for invoices twice. I am needing to apply this over payment to current due invoices. Can you please advise how I can enter? Thank you
The overpayment should be sitting as a credit on that customer account.
You can pay invoices with the credit that is available until the credit is used up - select the invoiice to "pay", see the available credit below, click on Credits and tick the credits to apply to this invoice. If you are not using it all enter the amount to apply in the Amt to Use column.
Jules