Q: How to fix permissions?

Hi,

I'm afraid I might have followed bad advice to solve a problem, which then got me into serious problems. Here's my "story":

I'm running Mac OSX 10.9.1 on an iMac (2.66 GHz Core 2 Duo). The computer is used by the whole family, so we have 6 user accounts.

1. Initial problem: The system requested an admin password every time I wanted to move an item to trash or away from the desktop.
2. After a bit of searching, I did the following:
   • Chose the Macintosh HD in a finder window.
   • Chose "Get info" and the Permissions-section.
   • Highlighted "System" and selected Apply all enclosed folders (this text might be slightly different in English, I run my system in Norwegian language)
   • This seemed to work, as I no longer need to type password for deleting/moving files. BUT NEW MAJOR PROBLEMS:
3. Now all other user accounts doesen't work properly any more:
   • No icons are visible on desktop of the other users
   • Finder windows on other user accounts closes by them selves whenever I try to do something
4. So first I went back to the user account in line nuber 2 above, where I had made the permission changes
   • Chose the Macintosh HD in a finder window.
   • Chose "Get info" and the Permissions-section.
   • Highlighted "System" and selected Reset changes (or whatever the bottom choice is in English)
5. No luck - problem still there
6. Ran Disk Utility, repair permissions twice - still no luck...

So if anyone have qualified suggestions on how to get the permissions right, please let me know.

Thanks a lot!!

Eldar

(Needless to say, but anyway: unqualified guesses are really not needed, as that's what escalated the problems from just having to type password to having 5 useless user accounts...)