You can set it into Default No by changing the code in the following file
mod\quiz\report\overview\overview_options.php
Searh for the following value and change the "true" value into "false"
public $slotmarks = false;
You can set it into Default No by changing the code in the following file
mod\quiz\report\overview\overview_options.php
Searh for the following value and change the "true" value into "false"
public $slotmarks = false;