It's nice to see you here in the Community. I'm here to share some information about the format that you'd like to have on the Accounts Receivable (A/R) Aging Detail report.
Currently, QuickBooks Online (QBO) doesn't have the option to separate each customer per column in the A/R Aging Detail report like the A/R Aging Summary report. This is mainly because the A/R Aging Details report is designed to show all your A/R transactions regardless of the customer, while the A/R Aging Summary report will show the total of all the A/R per customer.
If you wish for this option to be added, you can send feedback and suggestions directly to our Product Developers. QBO is constantly changing and evolving based largely on the suggestions and requests of users, like yourself. You can submit this from within your account by selecting the Gear icon and Feedback or by going to the following link: QuickBooks Online Feature Requests. I'm going to submit feedback from my side as well.