To edit a quiz, select a quiz by clicking on the name in the Draft Quizzes section of the main Quizzes page. The option to Delete, Copy, Finish and change the Owner/Co-owner of the quiz is available.
Users have the option to delete and edit questions from the quiz. The max total amount of questions can also be changed from this page, clicking on the number amount next to Total will give the option to change the value.
Users can only edit an unassigned quiz by sending the quiz back to draft with the Draft option. Once in draft the quiz will have the additional editing options.