Apple TV: Audio Won't Change To Airplay

Sometimes the sound works fine, other days the audio won't change from the built in speakers to airplay. I've tried to go into settings and changing it but it won't stick, it'll just keep switching back. I've tried restarting my computer and turning the apple tv off then on again but nothing changes. The picture transfers fine but the sound still plays from my laptop. I'm not sure if theres a way I can fix this problem or if I should return it and get a new one?

Any Suggestions?