Hi there,
The default for my site is for two column display, however for the Members page I have set it to three column display. Previously this meant that the three column display would flow down to the members profile pages. However this has now stopped and whilst the members page itself is three column the profile pages are default.
I’ve set up a test site with just buddypress and graphene installed to recreate this issue.
http://s521200750.websitehome.co.uk/