How to replace forum_new.gif?

[Lynne]

It looks like this is the image here:

<img src="$stylevar[imgdir_statusicon]/$forum[imageprefix]forum_$forum[statusicon].gif" alt="" border="0" id="forum_statusicon_$forum[forumid]" />

So, depending on the status, the image is changed from forum_old to forum_new (or one of three others). So, you could do a condition based on $forum[statusicon] to change the image if it is 'new' or you can make the names of your images fit that pattern and then change forum_ to whatever you chose.