Welcome to the Community, Charlie.
I'd be happy to help you customize your Transaction List By Customer report and add the column for Invoice Number. Here's how:
1. Go to the Reports menu.
2. Choose Customers & Receivables and then Transaction List by Customer.
3. Select Customize Report.
4. On the Display tab, type Num in the search bar and check to add the Invoice # column.
5. Go to the Filters tab.
6. From the Filters list, choose Transaction Type.
7. From the Transaction Type dropdown, select Invoices.
8. Click OK.
You can then run the report and check for the applied filter and column.
I'm also adding these articles if you want to customize and export reports in QBDT:
Feel free to reply to this post if you need further assistance. Have a great day ahead!