The organ is a terrific instrument for problem solvers. All of those buttons, knobs, pedals and whatsajigits can be combined in all kinds of terrific ways to create all sorts of different effects. There may be any numbers of jobs, but there are endless numbers of ways to get the jobs done.
On the other hand, this is precisely the sort of thing that scares the bejeebers out of young pianists-turned-organists. I remember the look on the face of one young lady pianist I coaxed to try the organ. The first time she sat at the bench I saw the same look of panic I've seen on the faces of countless individuals when faced with all of those buttons, knobs, pedals and whatsajigits. It was a face that said, gee, I really hope I don't accidentally hit the wrong button and blow up the whole church!
I've been playing the organ for nearly thirty years now and I've yet to accidentally hit the destruct button, so I imagine we're all pretty safe. It's possible that our organ doesn't even have one of those things.
Once you start to get the hang of all of those bells and whistles, though, you find that there is enormous room to experiment with sounds and sound combinations, and also just to find ways to make life a little easier.
This morning I was playing a funeral, which generally means I'm improvising. This is nothing difficult, just soft hymn settings with the occasional interlude. It was the end of the service and I was a bit tired, and not feeling particularly coordinated, even though I wasn't trying to do anything earth-shatteringly difficult. But in my mind's ear I wanted to put the melody of the next verse in the tenor voice, with a mildly cheesy mixture combination over a flutely accompaniment.
In the old days that would have meant to play the melody with the left hand on the upper manual, and the accompaniment with the right hand since it was mostly higher. There would be some crossing of the hands at times, but it isn't something I haven't done before. However, I may have mentioned that it's been a long week and I wasn't sure I was really up to not messing this up.
This is where fun with knobs comes to the rescue. Instead of playing the keys in their proper octave with the left hand trying not to come up against the right, I played it an octave higher with the right hand. But with an organistic slight-of-knob it didn't matter.
That's because we have a sub-coupler. It's the knob at the top of the picture below, marked "Swell 16." What that does is add the lower octave to the note you are actually playing. But I didn't want both octaves sounding at once, so I used the "unison off" knob next to it. That turns OFF the note you are actually playing, keeping the octave below. So I could play the Ab above middle C and what everyone heard was the Ab below middle C. Voila! Which made the entire passage easier because not only was I feeling particularly right-handed at the time, it also meant my hands wouldn't get in the way of each other, and I could get the effect I wanted.
This really took only a few seconds. Long enough for me to think I wasn't feeling very coordinated, realize there was a solution that would make things easier, pull the appropriate knobs and play the piece. But like many persons who are or were pianists, I had something of an aversion to all of those knobs and it took me a while to get over that and start making them work for me.