Overpayment received in foreign currency
You get an error of 'Receipt amount exceeds amounts allocated to invoices' when try applying an overpayment to a foreign currency invoice. You have to use dummy invoices to transit the additional amount received between the Overpayment Received and the Accounts Receivable account.
Assuming Singapore dollar is your base currency. You received a payment of US$10,960 from a customer for an invoice of US$10,690. This cause an overpayment of US$270 which you need to capture as an outstanding to the customer.
For illustration purpose, we create a current liability account and name it as 'Overpayment Received' (Check with your accountant for an appropriate name use).
To offset the full amount received, you create a dummy sales invoice of US$270 to the customer. This invoice debit USD Accounts Receivable and credit Overpayment Received account of US$270, which will add to the outstanding of US$10,690.
Then, record a receipt of US$10,960 into your USD bank account and offset both sales invoices. This receipt debits USD Bank US$10,960 and credit USD Accounts Receivable US$10,690 and US$270.
Next, record a dummy negative sales invoice (credit note) to reverse the US$270 from Overpayment Received account. This negative sales invoice debit Overpayment Received and credit USD Accounts Receivable.
You have an option to offset the credit note with the future sales invoice or send a refund to the customer. The 'Send a refund to debtor' feature is under the Command menu which debits the USD Accounts Receivable and credit USD Bank account.