users can edit others users comments in profile and social groups
 

not only in their own social group or own profile, but they can edit the comments of other people in someone else's profile, how can i avoid that? thanks

sounds like you've given normal users moderation powers - check your usergroup permissions

how can i change moderation powers for social groups and profiles? the users have normal permissions, i already checked and they don't have moderation powers in normal boards

That isn't what happens in standard vB - try disabling your plugins and see if you still have this problem.
Note: To temporarily disable the plugin system, edit config.php and add this line right under <?php