There is an issue where the global config is not taking effect on quizzes. Process: 

1.Set "show intro" quiz setting to "use global" 

2.Set global settings of "show intro" to "show"

3.Takes no effect on the quiz.

If you make the setting work on the local quiz it works. Process:

1.Set "show intro" quiz setting to "show"

2.Works. 

Here is a video outlining the issue: 

https://www.youtube.com/watch?v=swPLEisOv-c