Alright, so only the cut button must also turn it back on. And what if you switch to another set? Keep a side muted? And what if you mute left and right?
Then to the code, pfff, every heard of indentation? PRess CTRL+T in the IDE and see how that looks.
Next, did you heard of arrays?
Next, did you heard of arrays?
Next, did you heard of arrays?
You'll get the joke once you do 
With arrays you could have done the same thing in like 50 lines of code. Because now you simply repeat yourself for ever channel.
I ould strongly suggest to rewrite to code to use arrays. That would make implementing what you want also a lot easier.