Stop automatically matching payments to invoices

When I enter a payment from a client in Quicken HBRB in the "Invoices" account, the program appears to automatically match it to the oldest invoice(s) from that client. I want this to stop! These payments are not always assoicated with those particular invoices, as the client may be able to pay a down pament for a new job before he can pay the balance on the older job. In addition, if I enter a payment in the future and/or edit such future payment (such as adding new notes or changing any other field), Quicken again automatically assigns it to the oldest outstanding invoice. How do I get Quicken to stop this annoying practice?