How do I....? (solved)

When opening a Cubase project file from within a folder, it opens in Cubase 8…even if I have created it in 8.5…
How do I make Cubase 8.5 the default program…?

http://osxdaily.com/2013/08/08/change-default-application-open-files-mac-os-x/

Is a good start.
Also try Google keywords:

associate file types in macos
And
mac how to associate file types with programs


Thanks…found the solution.