Midi file import and concert pitch

Hi. I've had this problem before, but cannot resolve it in a similar way as the previous time in this instance. The midi file was the only version I had left of notation I previously captured. So, I imported it into MuseScore. All okay, but the key signature. It goes to everything but the correct key for each instrument. I toggled around, but in vein. I cannot transpose it, then is sounds wrong too. Kindly assist? Thanks. Peet