Hi there, debby4.
I appreciate you contacting the Community for support. I'd be glad to show you how to get the reference number to show on the report.
There are just a few steps to do this. Here's how:
1. Click the Reports tab in the left navigation bar.
2. Enter the report you'd like to view in the search bar.
3. Select the small Gear icon within the report, beside of the export button.
4. Place a check in the box labeled Num (short for Reference Number). This will create a specific column to display reference numbers.
5. Now you're ready to Run report.
I've got an article for you that offers helpful pointers on running and customizing reports in QuickBooks Online. You can check it out here: https://quickbooks.intuit.com/community/Reports-and-accounting/Run-Reports/m-p/185760.
Keep up the great work and please let me know if you have any other questions.