Quote Originally Posted by LadyJazzer View Post
No matter what I do, it doesn't change the key to Bb...
You will need to check that the song's key is in accordance with the chords before you try "Set and Transpose" as you have been playing around with this for a while now.
Song Edit>Info>Key sig... the song's chords might still show in the key of A, so change the key in the pickers (tumblers) to the same key they are in (presumably the key of A.) Then tap the Set key.
Then you should be able to change the key to Bb, by changing the key in the pickers again but this time tapping Set and Transpose, Done, Done, Save.

I am thinking previously you might have changed the key to Bb and tapped Set. In this case the Set and Transpose will not work as it thinks it is already in Bb (the song's key, not the chords.)
By resetting the song's key to the chords key first (using Set) you should be able to transpose successfully (to any key desired for the default key.)
It can get very confusing otherwise.