Hi @KristenWolters,
When editing a discussion, assignment, or quiz so that specific students get an extension, in the "Assign Access" area, make sure that you click on the "+ Assign To" button to create an additional entry. In that additional entry, you can then: (1) select the desired students and (2) enter the dates that you want (I typically leave the "Available from" blank). Attached are three screenshots.
You can restore the grades for everyone else by simply: (1) clicking on the "+ Assign To" button and (2) clicking on
the dropdown menu underneath "Assign To" and (3) clicking on "Everyone else". If you want, you can restore the original dates (something to consider if you want to lock others out again and if you are using a late grading policy. I attached a fourth screenshot showing adding "Everyone else" back.
More information is available in the How do I assign a quiz to everyone, individual students, or sections? - Instructure Community - 714 support article.
Does that help you?
-Doug
