hi rtjay, this will be caused by the update to flash 20 (the functionality was temporarily switched off in order to avoid hangs with the flash plugin) - adobe is ware of this and will hopefully ship a fix with one of their next releases.

my wife doesn't have that problem on her computer, the mute button is there using the same version 42.0

You can check this pref on the about:config page to see if it is the default.

• browser.tabs.showAudioPlayingIcon = true

how do i get to about:config?

You can open the about:config page via the location/address bar. You can accept the warning and click "I'll be careful" to continue.

• http://kb.mozillazine.org/about:config

Note that you may only see the mute button when the HTML5 media player is used and not when the Shockwave Flash plugin is used. You can check via the right-click context menu of the player area what kind of media player is used. A Flash based player shows a context menu with the Flash version.

i don't see how this link will help, this is the message i received:

The correct title of this article is about:config. It appears incorrectly here due to technical limitations in the wiki software.

You need to type the about:config text in the location/address bar where you also type the URL of the web page you want to visit and not in the search bar.

ok, i'm in about:config, but now what do i have to do to have the mute button activated?

You can start typing the browser.tabs.showAudioPlayingIcon text in the search bar on the about:config page to check if it still has the default value.

You can reset user set (bold) prefs via the right-click context menu to the default value.

the reset is greyed out and not an option