'Line in' audio expects an amplified audio source as input, such as a microphone attached to an external amplifier, or an iPod output through a stereo cable with a mini-plug on each end. Older MacBooks have two separate jacks for audio input and headphones.Next check the remote computer's sound from with the remote desktop program in the same way. Don't forget to check that your sound is not muted on the device you are using (by clicking the speaker icon in the lower right of the taskbar (or using the volume buttons if you are on a phone).

Concering connection problems: i have another Mac with a working TeamViewer. I reinstalled it, wiped all traces (caches, prefs.) and reinstalled it. No actual version did help, not even TeamViewer QS. Had another problem with another Mac with Maverixk on it: TeamViewer crashed directly crashed after starting it.Also disconnect any cables from the USB, Thunderbolt, FireWire, or 3.5mm audio ports. First, disconnect any external audio devices from your computer.

Teamviewer free not working