How do I add reference to imported sales invoices

Hi there, @mike281. 

It seems that you've posted twice in the Community with the same concern. My colleague already explained and provided steps on how to import sales invoices in QuickBooks Online. I'd suggest visiting this link for more details: https://quickbooks.intuit.com/learn-support/en-uk/transactions/re-how-do-i-import-sales-invoice-including-shipping-income/01/729156#M9847.

I've also added an article about handling sales forms for your future reference: Customise sales forms. 

Please know that you're always welcome to ask any questions here in the Community. Community family will glad to help. Keep safe!