I am sure there was a way to do this back in earlier versions.. hope it is just my memory which has gone and not this transpose feature.

I want the chord sheet to show Key of G but I want the accompaniment to play in Bb (equivalent to a capo 3)

Used to be able to set Key and chord sheet to G (by default), then when you transpose to Bb select NOT to transpose chord sheet. But this doesn't seem to work this way any longer. Now if you select not to transpose the chord sheet the music stays in initial key, dispite it indicating the key has changed in the Key dropdown box.