moodle/lang/en/help/quiz/repeatattempts.html

<h1>Each attempt builds on the last</h1>

<p>If multiple attempts are allowed and this setting is set to <b>Yes</b>, then each new attempt contains the results of the previous attempt.  This allows a quiz to be completed over several attempts.</p>

<p>To show a fresh quiz on every attempt, select <b>No</b> for this setting.</p>