No wonder, if you are new to trackers (?). Basically, there is no strict enforcement between tracks and instruments.
However, we have a little discussion going about how to associate tracks with instruments (located here), and I think your questions are very valid in that context.
Basically, my idea is to assign a name for the track if (and only if) you want to have a hard link between the track & instrument.
I think this sort of functionality could be achieved with a script - including the routing of MIDI notes into specific tracks.