[Oliver]

Wow great! It worked!!! Thank you soooooooooooo much
For everyone with the same problem: The Files are:

bp-activity-templatetags.php
entry.php

just search the for the div (e.g. firebug) to find the respective functions name in the entry.php. Then you search the function in the bp-activity-templatetags.php and change it the way you want