I just found it! If you have admin rights you can in the "Power Tools"

That's exactly what I was looking for! It drove me crazy that it would get marked complete and come off the to-do list when I put in 0's.   Do you have to do it for each individual assignment or ca...

Is there a way to change that for all activities at once?  

It was set to student submits. So it needs to be changed to receives a passing score?

In my course settings > Advanced Options I set a check for "automatically assign zero scores to past-due activities" and then unchecked the "mark auto-zeroed activities as complete. However it is ...