First, sorry for my English

I bought the pro version of the software. I really enjoy it, it's works like a charm.
But I've one question.
How is it possible to change the sound of the channel you are watching when it's in picture in picture mode?
I explain...
See this
Here
When the first channel is selected, I have the sound of it and it's ok BUT if I select another channel (the second, the third, ..), the sound disappear completely.
How can I fix it and is it possible?
Thanks for the answer
Best regards
Storn