You aren't limited to the reports that are built in to Flex. You can modify any existing report, and even create a report from scratch that has the information you need. Typically, you will request a custom report from Flex. But you can also design your own if you have some programming knowledge.
Requesting a Custom Report from Flex Support
To request a custom report, email email@example.com with your request details. Please refer to I'd like Flex to create a Custom Report for me for more information on how to proceed and what is required to process your request.
Designing Your Own Custom Report
Designing your own custom report can be very complicated and requires some programming knowledge. The following video explains the process of designing your own custom report: