Several quizzes in one project

I have a Menu design with 3 diferent subjects. When the user clicks subject 1 he is sent to slide #1, when he selects subject 2 he is send to slide #10  and Subject 3 sends him to slide #20. After he finishes each subject compose of 10 question slides he is sent to the final slide which is the .score. The problem I encountered was that the final score is always based on the total number of question slides which in my case is 30. To change this I thought I could change the number on the variable: pQuizInfoTotalQuestionsPerProject to 10 and everything would be fine, but no matter what I do I can't find a way to do this, Is there any widget or script to do this, or is it posible?

Thanks for any help.