marking videos as incomplete

Hi Trevor,

I understand that you would like the option to mark previously completed content as incomplete, but this is actually intended behavior that you are not able to. If something on the site were to glitch or if someone were to press a wrong button, that could put the progress that you have made at risk of being erased completely. If you would like to start a unit over, we recommend creating a new Khan Academy account.

I hope this helps!

Eva