audio/sound suddenly missing/really small

Hi, i've a problem with the audio sound when i connect teamviewer with my friends. I'm using windosw 8.1 and the remote is mac sierra.

the teamviewer works great, but yesterday, suddenly the audio sound is became really small and cannot be raised. (playing video or streaming etc)

i've looked at setting audio sound but none of it works.

when i disconnect the teamviewer, the remote (mac sierra) sound came back normal.

but when i connect again, the sound is smallll again.

what should i do?

thanks