Sound problems ACER Aspire Z1-602

Hi everyone, please help Smiley Happy

I bought and ACER Aspire Z1-602 for my office, it's with windows 10 of course. On daily basis I need to make Skype and Viber interviews and this is when the problem occurs. People from the other side cannot hear me eventhough I shout really loud.

I tried recording my voice just to check if the mike is working and it is- there is no problem. I tried test call on Skype, I hear my voice clearly. I tried calling my co-worker on Viber and what I hear is so quiet, I hear my voice from the other side really loud, but then my voice is so difficult to catch from people.

I tried to use headphones with a mike, with Skype so far it's working OK, but in the sound mixer, when I put the headphones, Viber doesn't appear as an app and when I make a call, I hear the voices through the PC speakers not the headphones.