In the Schedule tab, select the “daily” schedule.
You need to change the start time from 9AM or whenever you would like the repetition to start.
Note, however, the repetitions run inside the task. If you break the task to make changes or reboot the server, the repetitions won’t take place until the next day.
You can get around this by cloning the task N times, one for each cycle you need. Put them all on a daily schedule, with start times 9AM, 11AM, etc. and turn off the ‘run if missed’ option. That way if the task is stopped for whatever reason those other tasks will turn on automatically. But for most users using the repeat setting will be fine.
Note it’s not recommended to run tasks more often than 30 minutes apart, due to the way VSS internally cleans up in Windows.