audio issues on iPad

on this site i have set up using fullscreen.js I can't figure out how to get the 'afterLoad' function to trigger a new audio sound on my iPad. It works perfectly on desktop ( safari).

if you scroll down the will notice the audio track changes. On iPad the video and audio only pauses and plays (but it sort of works in that it does control stopping and starting separate audio and video tracks which is a hopeful sign that I've done something correctly).