There ar bo Course Permission Setting anyware as far I can see.
Please be more spesific of what you mean...
There is no number next to the student role in the user listing of the course.
In addition, do not understand what you mean by 'course-level overrides'..
Looking forward to your reply..
Course Administration - Users - Permissions
Then in the dropdown box, look for student:
If gradebooks have never worked on your site, then it may have been modified and might need to have the student role reset...
There is no 'Permissions' in User configuration settings.
The options shown are
Enrolled Users
Groups
Other Users
This is from the latest version of Moodle.
Permissions are accessable in the Navigation Participants options.
There there are an option in the Pariticicants menu (the right-hand side of the screen) to set the user permittions for the course.
Choosing 'Student' and set the 'View Grader report' to 'Prohibit', the correct gradebook appears for the students ('User report' and 'Overview report'