A best practice when using Levered is to keep all of your students on the same unit. You can move all of your students to the next unit by going to the Progress View tab
and then clicking the Move All button:
...and then selecting a unit from the first dropdown menu:
Then just click Reset All and they will move forward.
If you would like guidance on when to move your students to the next unit, read through the Course Overview for the grade level that you teach. If you are having trouble keeping your students on the same unit because they are moving at very different speeds, read about adjusting pass scores for individual students.