No vertical scroll bar during quiz

When I preview my quiz, my longer quiz questions go off the bottom of the screen and there’s no vertical scroll bar.

Consequently, when I put the questions at one per page, the next button is hidden and the user cannot move forward.

If I place all the questions on one page and use the overview to jump down to a question, there’s no way to scroll back up to the overview again, or scroll down to the next question.

I am using Firefox 24.0 on a Windows 7 computer.

I feel like there must be a setting I’m missing, but I cannot find it to enable the scroll bars. Any suggestions?

Thank you,
Katie

https://www.ads-software.com/plugins/wp-pro-quiz/