Change the template postbit in Postbit Templates with this:
{$ignore_bit}
<a name="pid{$post['pid']}" id="pid{$post['pid']}"></a>
<table border="0" cellspacing="{$theme['borderwidth']}" cellpadding="{$theme['tablespace']}" class="tborder" style="{$post_extra_style} {$post_visibility}" id="post_{$post['pid']}">
<tbody>
<tr>
<td class="tcat">
<div class="float_left smalltext">
{$post['postdate']}, {$post['posttime']} <span id="edited_by_{$post['pid']}">{$post['editedmsg']}</span>
</div>
{$post['posturl']}
</td>
</tr>
<tr>
<td class="trow1 {$unapproved_shade}">
<table cellspacing="0" cellpadding="0" border="0" style="width: 100%;">
<tr>
<td class="post_avatar" width="1" style="{$post['avatar_padding']}">
{$post['useravatar']}
</td>
<td class="post_author">
<strong><span class="largetext">{$post['profilelink']}</span></strong> {$post['onlinestatus']}<br />
<span class="smalltext">
{$post['usertitle']}<br />
{$post['userstars']}
{$post['groupimage']}
</span>
</td>
<td class="smalltext post_author_info" width="165">
{$post['user_details']}
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td class="trow2 post_content {$unapproved_shade}">
<span class="smalltext"><strong>{$post['icon']}{$post['subject']} {$post['subject_extra']}</strong></span>
<div class="post_body" id="pid_{$post['pid']}">
{$post['message']}
</div>
{$post['attachments']}
{$post['signature']}
<div class="post_meta" id="post_meta_{$post['pid']}">
{$post['iplogged']}
</div>
</td>
</tr>
<tr>
<td class="trow1 post_buttons {$unapproved_shade}">
<div class="author_buttons float_left">
{$post['button_email']}{$post['button_pm']}{$post['button_www']}{$post['button_find']}{$post['button_rep']}
</div>
<div class="post_management_buttons float_right">{$post['button_edit']}{$post['button_quickdelete']}{$post['button_quote']}{$post['button_multiquote']}{$post['button_report']}{$post['button_warn']}{$post['button_reply_pm']}{$post['button_replyall_pm']}{$post['button_forward_pm']}{$post['button_delete_pm']}
</div>
</td>
</tr>
</tbody>
</table>
Then in the User cp or Admin Cp do the normal changes to view the postbit in the horizontal way. If you already have it in that way then just paste the code!