How to Send an Invoice
1 - Go to the Sales menu and select 'All Bookings'.
2 - Select the Booking which you would like to send an invoice from.
3 - Select the 'Sales Invoices' tab.
4 - In the screenshot below, one of the invoices is in 'Posted' status, whereas the rest are in 'Draft' status. Only invoices in 'Posted' status will be able to have the generation of a Sales Credit. Therefore, select 'Post Invoice' on the invoice you would like to have a Sales Credit.
5 - If you now make a change to the booking, the result will be the generation of a Sales Credit and a new Sales Invoice.