An Eflat instrument is up a perfect 6th.

I don't remember when the P button showed up but Alto sax is +9, up a perfect 6th.

Bflat would show up in the key of G.

Forget the discussion of horns and the wherefore and the why start a new thread and Dr. Matt will lead you through some stuff, except forget the trombone. Too many variations of that thing.

Remember when you play a note on the horn, say your G. down is F# then F then E then Eb then D then D flat, then C then B then Bflat. 9 count 'em.

If you don't like the result you can go up or down an octave by pressing CTL ALT and 1, or CTL ALT and 2.

Or go back to concert pitch then change the key / let it transpose and then go back and change it +9.
You can use -3 too.

Most versions come with a classical song folder and some came with folksong folders.

Don't reinvent the wheel there are lots of songs, about 20,000 of them in band in a box format on the net.

I learned to play a G marching horn and a bflat baritone by myself, with Band in a Box, an OLD version, using the transpose feature. Works great. Even better after the enhancements in the later versions. And I was well over 50 when I started. (I do have background in piano and accordion.)

John Conley
Musica est vita