I am having a hard time using the instruments controls in guitar tabs. The controls are counter-intuitive in the extreme and the sound cheezy.

For example, I want to be able to isolate a single instrument in the tab for Eric Clapton's Cocaine. If I go to say Guitar 1 I can push two buttons. One says "S" which I take to mean "Solo" the other says "M" which I cannot decipher because pushing it doesn't seem to do anything.

I would like to hear only one guitar, I could care less about the bass and other crap that is going on.

Since UG doesn't seem to have any relevant 'help' outside of these forums I am hoping someone can smack me upside the head and give me some insight as to why these controls seem so incredibly opaque. I am old, but have been computer savy since about 1980.
The M button mutes the selected instrument
muting and soloing at the same time is like dividing by zero

doesn't the solo button do what you're looking for?
But boys will be boys and girls have those eyes
that'll cut you to ribbons, sometimes
and all you can do is just wait by the moon
and bleed if it's what she says you ought to do

If you're solo'ing a single track and you can't hear it, I'd suggest checking the volume and panning right next to it. It could be that it's turned way down.

If none of that works, get a new file for the tab as yours may be corrupted.