[Finale] Playback voices -- how to change?

[Blueyedtam64]

I have 4 staves set up for piano-like sounds, but I now want to see how they sound as horns, for example a brass quartet. So I would like to change the General MIDI implentation of the voices. Playing around with the staff instrument assignment really is not desirable, because I didn't wan't the instruments to transpose. For example if I change a staff to trumpet, it will become a transposing instrument when I use that approach. Nevertheless, I would like it to SOUND like a trumpet, trombone, etc. when I play it back. So in other words, I want to change the playback voices without changing the staff attributes.

A perusal through their write-ups so far has not yielded anything obvious I can do. Any suggestions on this?

Much appreciated;

Tammy