Running a Task Scheduler task as Administrator not a specific user.

If you are wanting to run the task as a native user (such as "OS Automation" or some other user ID you created), I typically log in as that native ID, set up a WF, POV and then any scheduled tasks while logged in as that ID.

But there may be other ways.

You can take a xml extract of the task scheduler and update the user name to the id you want to run it against and upload it back