There is no "Modified By" attribute present in report studio(insight reports)
One answer
Hi Sunanda,
As Jackie advised you as below, you can find "Modified by" in Operational data store-> Request Area-> Request History-> Modifier Name.
https://jazz.net/forum/questions/245772
You cannot find it under Operational data store-> Request Area-> Request, because modifier name is found in history tab in RTC WI.