Everything is super zoomed-in in MuseScore 2.3 AND the latest MuseScore 3. not an issue in any other application.
(macOS Sierra 10.12.6)
I'm using my laptop plugged into a TV. I opened MuseScore 2.3 (forget the exact version) and everything was incredibly zoomed in. I tried zooming out, and the score itself zoomed to a still-bad-but-not-unusable distance but the toolbars remained massive. I can't find anything in settings to reduce the size of the toolbars. This issue is present in every version of MuseScore I've tried, including the latest, and does still appear to happen when I unplug the HDMI and use the laptop's display, though it wasn't an issue before I first tried opening it while on the TV. This issue is not present in any other applications.