Ok I found the solution, if you want to have a picture uploaded in differents blogs but with same name lets say: author.jpg and you want that each author upload its own picture you have to hack includes->functions.php
Find these lines:
$dir = $dir; // . "/$y/$m";
$url = $url; // . "/$y/$m";
and delete them because the y(year) m(month) is the problem then you have to put in your file, lets say you want it in header.php
<img src="<?php echo get_bloginfo('siteurl'); ?>/files/author.thumbnail.jpg" width="XX" height="XX" alt="whatever" />
Just in case someone need it :D…
Bye…
Thank u so much alexleonard 🙂
But I am working with a version that do not have that option (wordpress mu) which complicated a little bit everything :'(
Does it have that option in another menu or submenu? I’m new in that wordpress version :0