Thanks for the very helpful answer!
I was under the impression there was no manual, just the tutorial at TIST. I can't find it in the program folder or anywhere. In most forum posts (here you are quoted:
you say there is no manual...not until the Pro version. Which is it, and where is it?
I know where those circles are (have used the old Tower program), but I was checking 24L/R and 25L/R, as those are indeed active runways. They are active for departures, and should be active for arrivals as well. If I have all 4 runways set to active for arrivals (as does happen real world during the busy pushes), then all 4 runways should be utilized. Instead, every single aircraft arrives on the inboards. That doesn't make sense.