Open up template postbit or postbit_legacy (Whichever your forum is set to)
Find:
Code:
<vb:if condition="$show['quickreply'] AND !$show['threadedmode']">
<a id="qr_{vb:raw post.postid}" class='quickreply' href="{vb:raw post.replylink}" rel="nofollow"><img id="replyimg_{vb:raw post.postid}" src="{vb:stylevar imgdir_button}/trans_40b.png" alt="{vb:rawphrase quick_reply_to_this_message}" /> {vb:rawphrase reply}</a>
<span class="seperator"> </span>
</vb:if>
Replace with:
Code:
<vb:if condition="$show['quickreply'] AND !$show['threadedmode']">
<a id="qr_{vb:raw post.postid}" class='quickreply' href="{vb:raw post.replylink}" rel="nofollow"><img id="replyimg_{vb:raw post.postid}" src="{vb:stylevar imgdir_button}/trans_40b.png" alt="{vb:rawphrase quick_reply_to_this_message}" /> {vb:rawphrase reply}</a>
<vb:if condition="$thread['firstpostid'] != $post['postid']">
<span class="seperator"> </span>
</vb:if>
</vb:if>