How do I upgrade (copy settings) from Cura 2.5 to Cura 2.6? On my Mac I've got two versions of Cura installed, in /Applications/Cura250 and /Applications/Cura262.

How can I copy my printer and profile settings from Cura 2.5 to Cura 2.6?
Hope this is all you need.
From the release notes page 


  Cura 2.6 - June 20, 2017 Local version folders. When installing a new
  version of Cura, a new local directory will be created to make it easy
  to access old configuration folders and return to old settings if
  necessary.


So if you know where your current 2.5 config directory is, you should be all set.