How do I set up or start an invoice number in Quickbooks Enterprise? QuickBooks automatically is a sets of your invoice number and increases it sequentially with each new invoice, but they you can adjust this number to anything you want to Setting your own invoice number can help to the keep invoices for different clients separate. QuickBooks is the continue to the advance your invoices by one number, so you will need to adjust this number for each invoice if you want to jump by other amounts. Customizing Your Numbers . To set the invoice number, first change the company setting. Click the gear icon in QuickBooks and then click on Sales Form Entry. In the Custom Numbers section, check the box next to “ Custom transaction numbers ” and then click Save.You can now edit all number fields on your sales forms, including the invoice number. After you edit a number in an invoice and either save it or send it, QuickBooks will remember...