When you enable one question at a time in your quizzes, students will receive only one quiz question on their screen at a time instead of all questions posted at once.
The student's view is exactly as you see it when you preview your quiz before publishing it. They will have to click the Scroll down to advance through the quiz. Once the question has been answered, the Scroll down the next question.
If you allow students to return to prior questions, they can Scroll up.
Students can also click the sidebar links for quicker navigation between questions.
If students leave a question blank, they will receive a warning message telling them that they will not be able to return to this question.