Hi
From what i can make out do this
Find in navbar template:
<if condition="$show['member']">
<td class="alt2" valign="top" nowrap="nowrap">
<div class="smallfont">
<strong><phrase 1="<a style='text-decoration: none' href='member.php?u=$bbuserinfo[userid]'>$bbuserinfo[username]</a>">$vbphrase[welcome_x]</phrase></strong><br />
<phrase 1="$pmbox[lastvisitdate]" 2="$pmbox[lastvisittime]">$vbphrase[last_visited_x_at_y]</phrase><br>
Change it to:
<if condition="$show['member']">
<td class="alt2" width="999" valign="top" nowrap="nowrap">
<div class="smallfont">
<strong><phrase 1="<a style='text-decoration: none' href='member.php?u=$bbuserinfo[userid]'>$bbuserinfo[username]</a>">$vbphrase[welcome_x]</phrase></strong><br />
<phrase 1="$pmbox[lastvisitdate]" 2="$pmbox[lastvisittime]">$vbphrase[last_visited_x_at_y]</phrase><br>
change the 999 to the size that you require, should work ok, just remember make a backup of the template before you start as i cannot be responsible if things go boobs up lol