[horde] prefs_init hook

[steffo76 at gmx.de]

Dear all,
 
I have a question regarding the prefs_init hook and the stickyness of the values it returns. My hooks.local.php in imp and horde return values for prefs like full name, signature and mail address. This works as expected but the prefs don't get saved after the user logs out. Is there any way to make the settings stick without the user having to manually save them ?
 
My setup involves horde groupware 5.2.10 and php 5.6
 
Thanks,
Stephan