transposing a MIDI file after import

I have an orchestral piece as a midi file, the midi has been made in the wrong key although all the music is correct ( Emin instead of F# min).
I start by selecting a new project, then import the midi, then enter the new key signature ( A) but the music does not automatically transpose to new key, Fmin, how do I do that so as to get rid of most of the accidentals ? thanks
I start by selecting a new project, then import the midi, then enter the new key signature ( A) but the music does not automatically transpose to new key, Fmin, how do I do that so as to get rid of most of the accidentals ? thanks