Trouble toggling sound output

I just bought a mac mini and set it up with 2 displays. 1 is hdmi to hdmi and is plugged into an entertainment console for my television. The other is thunderbolt to hdmi plugged into a monitor which has external speakers plugged into it. The displays are mirrored.

Either display works great with audio alone. Initially I could toggle the sound by going into sound under system preferences, but that no longer works. It may be because I downloaded some software, PTH Volume, to create a quick toggle (which also worked initially). At some point I stopped being able to toggle the audio output and now the computer simply picks one or the other at random on boot (or if I unplug one and leave the other plugged in, when I plug the second plug in, the audio sticks with the first plug). I'm not sure what I did, but I have tried uninstalling the software, which did not help.

Any ideas???

Update: The issue fixed itself... at least temporarily. While turning off the machine and unplugging everything did nothing, logging out into a new user name (where it then worked) and logging back into my own seems to have solved the problem.... go figure.

Update 2: There is no need to download 3rd party software, there is a shortcut built into the os (mountain lion at least): option + clicking on the volume button in the menu bar.

Thought about that keyboard shortcut but I was not sure it would work as a long-term solution. That shortcut has been around for a while.