Thats what the link at the top is for :P
If its really bugging you, go to AdminCP -> Styles and Templates -> Style Manager -> Common Templates -> Go to the footer box
Add in the Green code:
<br />
<div class="smallfont" align="center">$vbphrase[all_times_are_gmt_x_time_now_is_y]</div>
<br />
$spacer_close
<!-- /content area table -->
<form action="$vboptions[forumhome].php" method="get">
<table cellpadding="$stylevar[cellpadding]" cellspacing="0" border="0" width="$stylevar[outertablewidth]" class="page" align="center">
<tr>
<if condition="$show['quickchooser']">
<td class="tfoot">
<select name="styleid" onchange="switch_id(this, 'style')">
<optgroup label="$vbphrase[quick_style_chooser]">
$quickchooserbits
</optgroup>
</select>
</td>
</if>
<if condition="$show['languagechooser']">
<td class="tfoot">
<select name="langid" onchange="switch_id(this, 'lang')">
<optgroup label="$vbphrase[quick_language_chooser]">
$languagechooserbits
</optgroup>
</select>
</td>
</if>
<td class="tfoot" align="$stylevar[right]" width="100%">
<div class="smallfont">
<strong>
<if condition="$show['contactus']"><a href="$vboptions[contactuslink]" rel="nofollow">$vbphrase[contact_us]</a> -</if>
<a href="$vboptions[bburl]">$vboptions[bbtitle]</a>
<if condition="$vboptions['hometitle']"><a href="$vboptions[homeurl]">$vboptions[hometitle]</a> -</if>
<if condition="$show['admincplink']"><a href="$admincpdir/index.php$session[sessionurl_q]">$vbphrase[admin]</a> -</if>
<if condition="$show['modcplink']"><a href="$modcpdir/index.php$session[sessionurl_q]">$vbphrase[mod]</a> -</if>
<if condition="$vboptions['archiveenabled']"><a href="archive/index.php">$vbphrase[archive]</a> -</if>
<if condition="$vboptions[privacyurl]"><a href="$vboptions[privacyurl]">$vbphrase[privacy_statement]</a> -</if>
<a href="#top" onclick="self.scrollTo(0, 0); return false;">$vbphrase[top]</a>
</strong>
</div>
</td>
</tr>
</table>
<br />
<div align="center">
<div class="smallfont" align="center">
<!-- Do not remove this copyright notice -->
$vbphrase[powered_by_vbulletin]
<!-- Do not remove this copyright notice -->
</div>
<div class="smallfont" align="center">
<!-- Do not remove $cronimage or your scheduled tasks will cease to function -->
$cronimage
<!-- Do not remove $cronimage or your scheduled tasks will cease to function -->
$vboptions[copyrighttext]
</div>
</div>
</form>
<if condition="$show['dst_correction']">
<!-- auto DST correction code -->
<form action="profile.php?do=dst" method="post" name="dstform">
<input type="hidden" name="s" value="$session[sessionhash]" />
<input type="hidden" name="do" value="dst" />
</form>
<script type="text/javascript">
<!--
var tzOffset = $bbuserinfo[timezoneoffset] + $bbuserinfo[dstonoff];
var utcOffset = new Date().getTimezoneOffset() / 60;
if (Math.abs(tzOffset + utcOffset) == 1)
{ // Dst offset is 1 so its changed
document.forms.dstform.submit();
}
//-->
</script>
<!-- / auto DST correction code -->
</if>
<script type="text/javascript">
<!--
// Main vBulletin Javascript Initialization
vBulletin_init();
//-->
</script>