In addition to choosing the desired instrument as BSG indicates you can also choose a playback sound for it (quite irregardless of the chosen instrument definition). That is something you do in the mixer.
The possible sounds available to choose from in the mixer, come from soundfonts. And you can add those yourself to expand the choice of sound you have within MuseScore. See https://musescore.org/en/handbook/3/soundfonts-and-sfz-files for more info about how that works.
Comments
Type the letter "i" to get a menu of instruments you can add.
In addition to choosing the desired instrument as BSG indicates you can also choose a playback sound for it (quite irregardless of the chosen instrument definition). That is something you do in the mixer.
The possible sounds available to choose from in the mixer, come from soundfonts. And you can add those yourself to expand the choice of sound you have within MuseScore. See https://musescore.org/en/handbook/3/soundfonts-and-sfz-files for more info about how that works.