Teamviewer 14 sound problems - Win10

I have tried Teamviewer14 between 3 Windows 10 computers - in pairs.

On every combination, I can only get internet audio in one direction. In every case, the computer doing the 'controlling' cannot hear the operator of the remote computer.

I have been through all the usual audio settings and all appears fine.

I have just tried swapping over between 2 computers (both running the latest Win10) in my own premises - and the problem 'reverses' with no other settings changed. This would appear to confirm that it is not a problem of my causing.

Help/advice much appreciated.