Keeping invoice numbers in sequence when using on a network
When you create an order (manually or when importing) the next available invoice number is used.
If you change the invoice number format you should do this on all the networked PCs.
If you add a new PC to a networked version you should update these values from another of the PCs.
When an order is created the next available sequential invoice number is used. You can update the invoice number in the Import Orders dialog and Order details page on an order.