Hi Tessa,
You can try using the Override function to quickly make all slides flash as slow as you want them to.
Kindly refer to this article for instructions on how to use the Override function:
http://support.brillkids.com/entries/20608263-how-to-change-playback-settings-for-all-little-math-lessonsNote: In the Override Settings window, you'll find the "Auto Forward" settings in the "Common" tab.
I hope this helps!