Hi msperformance01,

QuickBooks Online (QBO) South Africa automatically assigns and sequences numbers to your invoices and quotes separately. Whenever an invoice is created from the quote, then it will populate a number in sequence.

You might want to check out this article to know more about changing the invoice number on sales forms.

Let me share this link in case you want to personalise your form designs in QBO: Customise your invoices, quotes and sales receipts in QuickBooks Online.

Keep us posted if you have further questions. We'll be around.