you have to enable task history.
Then these should be stored in the event file .evt file
then you should be able to go into ntevl and see it as a list event file type to be monitored.
If you open Event Viewer and go to: Event Viewer (Local) / Applications and Services Logs / Microsoft / Windows / TaskScheduler / Optional, you will see all the Task Histories. The .evt files on located under C:\Windows\System32\Winevt\Logs directory.
Hope this helps