sounds like your using the moderm post bit ?
the one shown in the image is the legacy .
in the user cp -> vBulletin Options -> in : Style & Language Settings :
find : Use Legacy (Vertical) Postbit Template and choose yes .. .
to check if this is the problem, on
this site in your user-cp -> Edit options : (
Your Edit options in the user cp )
at the very bottom of the page you can choose between the 2 diferent postbits.
and the style width also .