Users must be registered and logged in to comment not working

hi

Users must be registered and logged in to comment is not working at http://www.curetinnitus.org.

ideally i could do this:
http://wordpress.org/support/topic/disable-users-must-be-registered-and-logged-in-to-comment-on-certain-posts?replies=6

but that topic is closed.

but basically, no matter how i set the checkboxes for commenting and registration, the site still demands login to comment.

i’d like to be able to modify the settings. ideally per post or page — but at least for the whole site.

best,
dainis