By default, MediaMonkey for Windows uses a set of rules to guess any file properties that are not defined in the tags from their folder/filenames. You can disable this by disabling Infer Properties under Tools > Options > Library from the Main Menu. You can manually get tags from folder/filenames by using Tools > Tag from Filename (Auto-Tag from Filename in MediaMonkey 5 and older).

If MediaMonkey for Windows is regularly guessing track properties incorrectly, those rules can be easily changed. The rules MediaMonkey for Windows uses to infer properties are stored within the [SongMasks] section of the MediaMonkey.ini file. To change these rules:

1. Close MediaMonkey for Windows (so that it doesn’t overwrite any of the changes)
2. Back up the MediaMonkey.ini file.
3. Open the MediaMonkey.ini file inside a text editor such as notepad
4. Edit, re-order, or delete the masks in the [SongMasks] section of the file. The variables are not documented anywhere, however, it’s fairly easy to figure out what they are by comparing masks in the MediaMonkey.ini file to those which appear in MediaMonkey for Windows. Some of the basic ones are:
   %A=Artist
   %L=Album
   %T=Track#
   %S=Title
5. Save the MediaMonkey.ini file.
6. Start MediaMonkey for Windows