I'm not sure what usergroup image you are talking about, but I do know the rank code:
HTML Code:
<if condition="$post['rank']"><div class="smallfont">$post[rank]</div></if>
So, find that code and since you say the usergroup code is above there, take the code above that line and move it to below that line. (My postbit code shows the usertitle being above that line, so I'm guessing you have custom code.)