How to enable and disable showing “previous question’s answer”?
Scored quizzes proides feature to show or hide previous question’s answer. You can set this option in the create/edit quiz page in accessiblity tab.
Set the option “Enable” in “Show answer after each question” : (See the screen shot below)

Enable previous question's answer
To disable you can choose the “Disable” option in same:

Disable previous question's answer