To edit Preferences (the appearance and general behavior of MuseScore), go to Edit→Preferences.
These are divided logically into sections (see below); notice also the three buttons at the bottom of the window:
You can specify your language, and autosave interval in “General”. See also Language.
“Program start” allow you to choose what, if any, score you want displayed in the edit window after launching.
“Folders” allows you to customize locations for any user folders (though it’s a good idea to leave them at default to start with if you are a new user).
Choose between light and dark options, and specify the accent color; there is also a high contrast option for visually impaired users.
The system font is also the default for the MuseScore UI, but you can alter this if desired—and the font-size.
You can set the score paper/color option and the background. For visually impaired there is an “Invert score” option which inverts the score colors (white to black and vice versa)
Specify the default zoom level of the score, and the mouse zoom precision. Also how you want your score pages to scroll, and the degree of precision of mouse selection.
Here you can choose how MuseScore sounds when you click on or advance to a note. And whether you want notes outside the playback range of an instrument to be colored.
Here you can map certain keys of your external MIDI keyboard to certain actions. For example to start or stops score playback, set note-entry duration, and so on.
Customize the default order of instruments in your score.
Specify your audio and MIDI input devices.
Specify the way that MuseScore handles the import of MusicXML and MIDI files. You can supply a style file covering every aspect of the score.
See Keyboard shortcuts for more information.
By default MuseScore automatically checks for updates when online. You can turn this off by unchecking the box.
A number of specialized options can be accessed here, such as voice color, and palette behavior.