Q: Can't get the volume to work on my tv when my iMac air is plugged into it

Hello matthewflatwoods,

Thanks for using Apple Support Communities.

From your post I understand that you have plugged your computer into your TV to use as an external monitor, and the sound is not functioning.  In order to have the cabability to transmit both audio and video through the Mini DisplayPort, your computer needs to be one of the following:

These Apple computers supply multichannel audio (up to 8 channels) and video signals over Mini DisplayPort:

• MacBook Pro (Retina, Mid 2012 and later) 1
• Mac mini (Mid 2010 and later)1
• Mac Pro (Mid 2010 and Mid 2012)
• Mac Pro (Late 2013)1
• MacBook (Mid 2010 and later)
• MacBook Pro (Mid 2010 and later)
• MacBook Air (Late 2010 and later)
• iMac (Late 2009 and later)

About Mini DisplayPort to HDMI adapters - Apple Support

If your computer fits the requirements, then please check the audio settings on your Mac, to ensure that the TV is selected rather than the built-in speakers.

OS X Yosemite: Adjust your computer’s sound output settings

Take care,

Alex H.