Not sure what 'puter you are using but on my mac there is a C4/C5 etc ‘Preference Folder’.
(I’m sure there is something similar on a PC or Lin box).
Moving or renaming that folder forces Cubase to build its own new Preference folder.
That way C6 will not be able to get (steal) any info from older versions and
it will build a fresh C6 preference folder.
That being said,
sometimes a user might want older preference files to be ‘read’ by a new programme.
Example: things like ‘Key Commands’ etc don’t have to be written (by the user) again.