[Simon Lloyd]

You'd have to edit your forumhome_forumbit_ templates, look for <if condition="!$show['collapsable_forums']"> and follow what i've done below, my forum id that i'm collapsing by default is 12, if it's more than one forum to collapse then you'll have to us an IN ARRAY if condition.

<if condition="!$show['collapsable_forums']">
<!-- CHANGED COLLAPSED BELOW -->
<tbody id="collapseobj_forumbit_$forumid" <if condition="$forumid == 12">style="display: none" <else /> style="{$collapseobj_forumid}"></if></if>
$childforumbits
<if condition="!$show['collapsable_forums']">
</tbody>
</if>
</if>