Save as ...
Sometimes, but not always, when Save As in Standard Midi File format using QuickTime Player it plays back at double speed.
I can slow to correct speed by using the QuickTime A/V Controls but slowing down is not always possible using other players.
Comments
A sample file (the actual score) would help. I'm guessing perhaps there is no tempo text specifying the desired tempo, and instead you might have been relying on the Play Panel, which allows you to override the playback speed within MuseScore, to change tempo.
In reply to A sample file would help. by Marc Sabatella
Thank you Marc you've hit it right on the head.
Richard