Hi Martin,
Yeah, chord naming can be tricky, because depending on the context of the surrounding music (eg. the key signature, and how the music is "moving"), the chord name can be different for the same three (or more) note chord
Composer does a "best guess" based on that paradigm. However, it's not perfect (we seem to always be tweaking it)
Fortunately, you can override the "not so best guess" that it makes simply by double-clicking the chord name and typing in what you want. Composer will honor that edit, and keep it "musical" in the score (eg. if you decide to change the key of the piece, that edited chord name will also change as will any others that are entered/recorded/edited).
ttfn,
Sherry