The option to not use the internal synthesizer does not work

I think this is a bug, because when I try to change the preferences to not use the internal synthesizer, and click Apply, and then Ok, it still does, until I switch to another instrument. Also, it says that I must restart MuseScore, but once I close and reopen MuseScore the setting is back to using the internal synthesizer. Finally, I think MuseScore is still using some form of internal rendering because it seems to fade instruments out, whereas saving as a MIDI file and playing it with Windows Media Player gives "sharp stops". I'm using version 1.2 on Windows 7.