Shared Calender entries alwas on busy


i hopefully used the right category.

This is our situation:
- ownlcoud 9 installation
- calender app
- microsoft office 2013
- CalDav Synchronizer
- 7 User
- 7 calender
- every calender is shared with every user (only read)

now everybody can see all the events from everybody in the outlook calender.
but you can see the title and more from every event from the other users.
only you choose "show only busy" in owncloud, then there only "busy".

can you say that every event is only on busy in the other calender?
somewere in the code or somewere else?

mhhh i hope i used the right words to explain my problem.
i can wirte it down in german if you want.

best regards