You should have something like this on index.php:
if (!$cookie['is_guest'] && $cur_forum['last_post'] > $cur_user['last_visit'])
{
if ($cur_user['show_img'] == '1')
$icon = '<img src="img/'.$cur_user['style'].'_new.png" width="16" height="16" alt="">';
else
$icon = '<span class="puntext"><b>?</b></span>';
}
else
$icon = ' ';
if (!$cookie['is_guest'] && $cur_forum['last_post'] > $cur_user['last_visit'])
{
if ($cur_user['show_img'] == '1')
$icon = '<img src="img/'.$cur_user['style'].'_new_on.png" alt="">';
else
$icon = '<span class="puntext"><b>?</b></span>';
}
else
{
if ($cur_user['show_img'] == '1' || $cookie['is_guest'])
$icon = '<img src="img/'.$cur_user['style'].'_new_off.png" alt="">';
else
$icon = ' ';
}
1) BACK UP :). It's a single file, but back it up.
2) I've removed the width/height setting.
3) If you want different images for different styles (CSS) you'll have to create them all. I use a single style (custom) so I removed the $cur_user['style'] code.
Change the code, then rename img/new.png to img/new_on.png and create a img/new_off.png that suits your tastes.
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Edit: The "dot" shown above has a code (& + #8226 + semicolon), look at the source because the forum it's converting it.