Hi Koyal,
Once a student starts accessing a quiz, any edits done to the quiz don't affect that attempt. So if you change the Until date after they had started it's still going to close them down at the original date. This is also try for questions. Lets say you create a quiz with no questions (just getting it ready) and Publish it. Student A sees the quiz and clicks on it to start; seeing no questions. You come back later and finish work on the quiz by adding the questions. Student A comes back to take it and they still see no questions. This is because it's still delivering the same exam they started. In this cases the student would need to submit it and start again to get the edited version. And the quiz would need to be set to allow multiple attempts.
I share that explanation because I think that is why some were auto-submitted and it also could explain why some have the 100%; if all of the questions were not there initially when they began.
At any rate, if you ever have questions that need to be manually graded you will need to go in through speedgrader and grade them. I don't believe simply adding 100% to the gradebook is going to work because the quiz still sees some questions as being ungraded.
Rick
This discussion post is outdated and has been archived. Please use the Community question forums and official documentation for the most current and accurate information.