What type (portable, installer, or Windows Store) of MusicBee are you using, and what version (3.2 etc)?
1. If it's the Portable, the files will be in the MusicBee\Appdata folder wherever you installed it to
2. If it's the installer the files will be in c:\users\(you)\appdata\roaming\MusicBee folder
3. Don't know about the Windows Store version except that it's in some bizaare path Windows Store uses, search the forum and you will find that info.
You can also just do a Find/Search in Windows Explorer/File Explorer (set it to also check hidden files/folders) for MusicBee3Settings.ini/bak. I'm assuming that you are using at least the 3.x version of MB for the name of the settings file.