Thanks for getting back to us, Ilana.

While the backorder option isn't available in QBO, you'll want to pull up the Estimate & Progress Invoicing Summary by Customer report. It includes estimates by customer, invoiced amounts, and remaining amounts to the invoice.

To pull up the report:

1. Select Reports from the left navigation bar.
2. Go to the Standard tab, then location Sales and customers.
3. Click Estimate & Progress Invoicing Summary by Customer to open it.
4. Filter the Report period to see the exact transaction.
   
5. You'll then see the progress of the estimate.

After that, you have the option to click the Save customization button to memorize the customized settings. This way,  you do not have to go through the customization process again.

Check out the Customize reports in QuickBooks Online page to learn more on how to get the data you need.

Let me know if there's anything else you need. Just tag my name and I'll get back to you.