Is there a 'working' solution for mute/unmute the video or the whole course?

Hi, I'm using the code below to mute/unmute my video on the course in storyline 3: 

var appState = require("helpers/appState");
appState.onToggleVolume();//mute/unmute
console.log(appState.volumeToggle);

But it fails to work if you open a new tab on your browser (the code runs but it doesn't work properly )...

I'm looking for a working solution which is reliable (Not necessary toggling,  a code for muting a code for unmuting is fine too.)

I really need your kind help.