I have 2.9.1.0 (in the About section), but 'review update' tells me (in a pop-up browser) I have 2.9.0.7, and that the most recent version I can update to is 2.3.1(of course).

The web update wizard, which pops up when I push 'install update', says after I push 'next'(and I quote) "You already have the most recent version of Notation Composer 2.9.1.0 on your system".

Hope that clarifies,
~Daniel