How do I stop acrobat pro/std 2015 (DC) from asking if you want it to be the default app for PDF every time it launches?

I know there is a check box to not ask again inside the application.  I a trying to set it for users when it installs so they are not prompted.  The customization wizard only has options to set a default or let app installer decide.  I could not find reference to a registry entry for this anywhere.