Hello there, Sonia Muller.
Currently, in the Customise report feature the Rows/ Columns feature can't be modify as what you would like it to be. There's just no option to put it specifically in a row or in a column position. The Payment date of the invoice is listed in a row position. No worries, I'll send this to our product developers as a feedback so that they can assess this and include this in the future update.
You can still continue to target getting the report with the Customer Invoice number and the Payment date. Here's how:
I have here a screenshot for your additional reference.
I include this article to help you figure out the best way to customize your financial reports: Customize reports in QuickBooks Online.
Loop me in if you need anything else. I'll be a few clicks away. Stay safe.