If you accidentally published a quiz that needs to be corrected, you can use quiz regrade to edit existing quiz questions and tell Canvas to recalculate student grades.

Quiz regrade only works with specific quiz question types and only applies to students who have already taken the quiz. Adding or removing a question does not trigger the quiz regrade feature. Additionally, changing the point value for a quiz question also does not trigger a quiz regrade; the student's submitted quiz will show the updated point value, but the current grade won't change in the Gradebook. If you have edited your quiz in one of these three ways, you should moderate the quiz and let the student retake the quiz.

This feature only applies for students who have already taken the quiz and only the existing quiz questions have been changed.