[pmwiki-users] How do you activate Site.Preferences?

[marc]

How do you activate Site.Preferences (as I would like to change them)?

I can apply the changes per user - by effectively doing

?setprefs=Site.Preferences

but I don't understand how the site-wide preferences can be applied by 
default and the amended to taste. I see that the initialisations take 
place in prefs.php ? although recent changes doesn't work work here ? 
but changing values there is a Bad Thing. I presume I can change things 
in config.php, but then what is the purpose of Site.Preferences?

Perhaps part of my confusion is that the settings in Site.Preferences 
are different to those in prefs.php. Dunno.

Confused.

-- 
Best,
Marc