System date format not changing

[bins]

if I go to
System Locale Settings:

and change the format to EU/UK style, it does not save.

If I do it at user level, it does!

EDIT:
I have also noticed that Subpanel items per page: does not change, either!

[dpatech]

Is your config.php writable? I would check file permissions on this file and see if they allow the user account being used for apache to modify the file.