If you are making edits in File > Project properties, then those changes are not reflected in the fields on your score (Title, Subtitle, Composer, Lyricist). You have to edit those fields directly on your score as well, which is tiresome. But AFAIK MuseScore has always worked like that.
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Double-click the text to select it. Then edit the text by deleting what doesn't belong and typing what does.
If you are making edits in File > Project properties, then those changes are not reflected in the fields on your score (Title, Subtitle, Composer, Lyricist). You have to edit those fields directly on your score as well, which is tiresome. But AFAIK MuseScore has always worked like that.