sometimes the chromebook gets confused between the speakers and the headphones
click on the bottom right hand corner to open up the following (once the person is logged into the machine)
see screenshot
Speaker should show a picture of a headphone- click on the arrow next to the headphone and make sure that the green check mark is
next to the headphones and not the speaker - if it is clicked on speaker, click on the headphone and it should switch it. (sometimes it gets stuck) (If no headphone exists, try to wipe the machine and reenroll it)