Hi Lorraine Horine,
Thank you for your question!
Yes, you can change the font size of the questions and answer options in a quiz included in a PowerPoint presentation. To do that, you just need to go to Slide View --> select a text box --> change the size (please see Screenshot 1).
You can change the font size on one slide and then apply it to other slides using Themes. Here are some help docs: https://docs.ispringsolutions.com/ispring-quizmaker/managing-themes-35667201.html.
Hope this helps!