Question engine upgrade helper
From MoodleDocs
The question engine upgrade helper is an admin tool for sites which have been upgraded from a pre-Moodle 2.1 version. Moodle 2.1 onwards uses a new question engine.
A site administrator can run the question engine upgrade helper in Settings > Site administration > question engine upgrade helper.
Note: You can reset any quiz that has been converted and then re-do it, but you should only do that if you have a good reason to do so and you don't have to.