Next and Back buttons can be added in a quiz to provide a flexible flow within questions. 

Step # 1

In any questions added, click on the Edit on Builder button.

Step # 2

Click on the Popup Properties menu located at the left column.

Step # 3

Turn on the Use Next Button and Use Back Button toggles to enable the buttons.

Note: the Back button is enabled throughout the quiz, however, the Next button will be enabled when a question is not a required question. If the question is required, the next button is displayed but disabled (grayed out), and can be clicked once a question is answered.