Transposing from B flat Major to A flat Major
Besides changing the Key signature from 2 flats to 4 flats, what must I do with the notes? Accidentals? I changed the key signature from 2 flats to 4 flats and did nothing else in "Noteworthy" (music software) and upon playing it, it did not sound correct.
I need to do something else.
Comments
To transpose you need to, hold it, transpose, not (just) change the key signature.
Put the key signature back to what it was and instead use [Tools]>[Transpose]. Select transpose "To key" and specify the new key. Make sure you have "Transpose key signatures" option ticked and if you have chord symbols also tick the "Transpose chord symbols" option. Then press the "OK" button and Hey Presto!
See https://musescore.org/en/handbook/3/transposition#automatic-transpose for more details of the clever things MuseScore can do with tranpositions.