I've figured this out after struggling with it repeatedly! The behaviour occurs because of the native Mac keyboard shortcut Cmd + : for spellcheck: https://support.apple.com/en-gb/guide/mac-help/mchlp2299/mac To solve it, go to System Preferences / Keyboard / Shortcuts, click on "App Shortcuts" and add new shortcuts for the commands "Bigger" and "Smaller" as Menu Titles (spelled exactly that way) for the App Evernote. E.g. Cmd + Option + . and Cmd + Option + , work for me.