For those having trouble with signatures in quick replies. Open showthread template and search for
Code:
<if condition="$bbuserinfo['signature']">
<div style="float:$stylevar[right]"><label for="cb_signature"><input type="checkbox" name="signature" value="1" id="cb_signature" tabindex="5" checked="checked" />$vbphrase[show_your_signature]</label></div>
</if>
And delete that.