Allowed number of attempts

Dear All,
In my site I created quiz content and set Allowed number of attempts.

1. I set allowed number of attempts is 5. I test with a student user take a quiz 5 times. The user can't access to that quiz more time. I want to reset allowed number of attempts for the student. So, they can they can take the quiz 5 times again.
   How to do that?
2. I want to choose allowed number of attempts from 1 to 20.
   How to do that?

Thank you so much,