Hi Dave,
You can change the default maximum allowed number of attempts for all problems. This is controlled by $problemDefaults{max_attempts}. The default is $problemDefaults{max_attempts} = -1 which means unlimited attempts. If you change this in localOverrides.conf (for which you need access to the server) it will make the change for all courses on your server. If you change it in course.conf (which a course professor can do) it will make the change for that course only. In either case you need to add the line
$problemDefaults{max_attempts} = 10;
if e.g. you want to set the maximum allowed number of attempts to 10.
Arnie