alright, i found the solution to change the thumb size:
open "photoplog_thumbs_horiz.php" file (or if you are using vertical one open "photoplog_thumbs_vert.php").
Find the line that starts with:
PHP Code:
<img src=\"".$photoplog_location."/file.php?".$vbulletin->.....
At the end you will see w=s\", make it w=1s\"
Again, at the end of the line, after border=\"0\" add width=\"yourchoice\" where yourchoice is the width you want. So in my case, that line looks like this:
PHP Code:
<img src=\"".$photoplog_location."/file.php?".$vbulletin->session->vars['sessionurl']."n=".$photoplog_fileid."&w=1s\" border=\"0\" width=\"175\" />