Allow me to chime in and provide another option or report to run to show the payment method, @ksottile.

I appreciate you trying the steps provided by my colleagues to run a Customer Detail report in QuickBooks Online.

Since the one you have tried does not show any information on the payment method, I recommend running the Transaction List by Customer report.

Here's how:

1. From the left menu, choose Reports.
2. Enter and select the Transaction List by Customer in the search box.
3. Choose the date range by clicking the Report period dropdown arrow.
4. Click the Group by icon and choose Payment method from the dropdown.
5. If the Transaction type column is not showing, you can add it as a Filter.
6. The report should now show the Payment method in the first column and the total for each method.

You can also check this article for more information on customizing reports: Customize reports in QuickBooks Online

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