Quiz Help

First time creating a course where user must pass with 80% correct answers. When user does not pass, they are only given the options to "review quiz" results or "exit" the course. Can someone tell me what I need to do to allow user to retake the quiz? The course is set up where the user must complete 3 modules within the course, in order to take the quiz. In this case, the 3 modules continue to show the user completed them BUT they are not given the option to retake the quiz. How do I fix it? Thanks!