d3forum has overriding system of preferences.
eg) Only "Q&A forum" has "solved" feature.
In module's preferences:
use solved [ ]yes [x]no
use_solved:1
allow_html
allow_textimg
allow_sig
allow_sigimg
posts_per_topic
hot_threshold
topics_per_page
use_solved
allow_mark
allow_hideuid
viewallbreak
selfeditlimit
selfdellimit
css_uri
anonymous_name
icon_meanings
guest_vote_interval