A payment with a due date means that the sale will be paid later than the closed date of the sale.
You have 2 options :
In 'Settings/Users/Access Management', enable the right: 'Authorize deferred payments'.
When you select the DIV payment method in a sale, you can link each payment line to due date.
When you receive the payment, go to the 'Customers/Due dates' tab, where all payments to receive are listed.
Click on the 'Payment done' button on the payment line received and confirm the date of payment.
In each End of day report, you will find: – all unpaid deferred payments with a due date at the date selected. – and all deferred payments received at the date selected.
If you have already closed the day of a sale with a deferred payment, you cannot change anymore the payment method used for the deferred payment. You will have to cancel the initial sale and re-enter the sale on the current day.
The initial sale is closed with the CRED payment method (on account sale). More information.
When you receive the payment, go to the Customer form and add a deposit in the 'Store credit' section for the payment received.