I'd be glad to join you here and help you get all the details that you need, mjkahn.

You can run the Invoice List report. This will give you a list of all invoices whether paid or not. Then, customize it to include the payments that were applied to the transactions. 

Here's how: 

1. Go to the Reports menu and select Invoice List.
2. Click Customize in the upper-right hand corner of the report.
3. Scroll-down to the Filter section and check the box for Transaction Type.
4. Click the drop-down list beside it and check the boxes for Invoice and Payment.
5. Select Run report. 

Please note that the reference number is shown under the Num column. 

I'll be sharing these references as well in case you need more guidance when running reports in QBO:

• Customize Reports in QuickBooks Online
• Common Custom Reports in QuickBooks Online

Feel free to join us again in the Community if you have other questions for us. We'll make sure to answer them for you.