midi in orchestral score

I imported an orchestral score from XML...perfect, as usual. That is such a wonderful surprise. But, I cannot find where to see the midi setting for each line of the score. Nor can I figure out how to set the midi playback channel for each of of a newly created score or change the midi definition of the lines of an existing score. I use VST instruments that necessitate being able to assign midi channels to each line as desi

It must be something glaringly obvious, so much is right at hand in MS, but I can't find red.that!