Click This Account, and then type the user account that will run tasks that are scheduled by using the at command.
In Password and Confirm Password, type the correct password for the account.
Notes
The AT service is available only on Windows NT.
Optionally, you can click System Account. If you do this, Task Scheduler runs the at command tasks by using the LocalSystem account, which requires administrative rights.
The user account you specify must have the appropriate permissions to run any tasks that you schedule by using the at command. For example, if you schedule programs that can be run only by administrators, the user account you specify must be an administrator account.