Thank you very much for your quick reply, Acrylian!
I have UTF-8 everywhere, in themes, in database fields, but I cannot use "ß" directly, "Hauptstraße" would turn into "Hauptstraf#376;e".
I always have to write for example "& b u l l ;" or "& e u r o ;" or "& m i d d o t ;", or the sentence will be cut at this char. In admin this is done directly after save. In frontend it first shows up like "Hauptstraf#376;e", if you leave the page and come back it is "Hauptstra".
And I could do this only in textboxes in admin backend but not in textareas (I guess this is what you missed) before I changed admin-functions.php.
Funny is that there is no problem to type äöü or even <> directly from keyboard.
Just what I would like to know from you is where I can find the code which is responsible for textboxes and textareas in frontend when logged in as admin and how to change the code. Because if I type "& e u r o ;" in any of the input fields it will be shown as € in frontend next time I edit it.
If I save that, the sentence will be cut before this char.
May be like this: '.html_encode($UnknownVariable_WhereDoIFindIt, $striptags=false).'?
Yours,
Lilly