Hello @BeckyV1885,
Thank you for reaching out to us here in the Community space. I can help you customize the Customer Contact List report in QuickBooks Online.
The option to directly include a column for the last transaction date in the report is unavailable. As a workaround, export your data to Excel and add the missing information manually.
You'll need two reports to come up with what you need from QuickBooks. I recommend using the Customer Contact List and Transaction List by Customer report for the dates.
Check out this screenshot for your visual reference on how to export a report:
For the second report, include the Data column before the export process (see additional screenshot below). This way, you can get a copy of the dates and merge it into your Customer Contact List in Excel.
Also, you can create custom reports regularly and schedule them to run automatically. I've included a link you can use as a reference: Customize reports in QuickBooks Online.
Glad to answer any other questions you might have about the QuickBooks Online platform. Visit the Community space again, and I'll help you out.