Hi KM3B5,
Once your Square is synced to QuickBooks Online, there's no need to create invoices or sales receipts. QuickBooks captures them as invoices and payments, and they are downloaded nightly. Please see the video about syncing with Square: https://quickbooks.intuit.com/integrations/square/.
You can also check this link for more information: Sync with Square.
Please let us know if you have other QuickBooks concerns. Thanks.