Instrument change with soundfonts
So when I have a soundfont installed, the Clarinet is automatically set to First Violins and I have to manually change it to the Clarinet sound in the mixer. This is fine except for when I want to change to A clarinet, the part makes no sound. I imagine this is because it is set to First Violins, except there's no way to change this in the mixer.
Comments
Most likely: The preset layout in the soundfont you are using is not GM-compliant.
Musescore's instrument-list is based on GM-compatible soundfonts.
So, you have no option but to change it manually.