I have already sent invoices that are not on QB. Do I have to send another Invoice for it to be part of my QB accounts?

Hi chris-cbproducti, thanks for your post 🙂

The invoices in QuickBooks Self-Employed are non-posting, meaning they don't impact any reports or accounts, instead, any income should be recorded and marked as 'Business income' on the Transactions page - so you won't need to worry about adding any old invoices, just the payments themselves.