I downloaded Schubert's 'Die Forelle' from NWC Scriptorium. (Brilliant incidentally). Transposed successfully both staves of the accompaniment down 3 semitones from D flat to B flat.
However, when transposing the voice line, it showed both the transposition and the original. Any suggestions please (apart from doing it all manually)?
I wonder if you haven't got a pair of layered staffs there? Go to the view menu, and uncheck allow layering.
Thanks a lot, David - it worked.