Maybe it is a wrong configuration, because in this forum it works well.
If I change the encoding in the logbook entry I get "Submit modified ELOG entry?",
and after clicking OK the entry is closed. Because this behavior is on all loggbooks
it must be a global config entry, but I dont know, which.
Here is the GLOBAL section:

Expand Selection page = 1
URL = http://sapelogs/
Date Format = %d.%m.%Y
Time Format = %d.%m.%Y %H:%M
Reverse Sort = 1
Menu commands = New, Edit, Delete, Reply, Download, Find, Last day, Last 10, Select, Copy to, Config, Admin, 
Login, Logout, Help
Find Menu commands = New, Edit, Delete, Reply, Download, Find, Last day, Last 10, Select, Config, Admin, Login, 
Logout
Password file = passwords.txt
Login expiration = 2
Admin user = ME
Suppress Email to users = 1
Self register = 0
Logout to main = 1
admin textarea = 150,45
Entries per page = 100
Mode commands = 1
Use Lock = 1
Supress Email on edit = 1
Supress default = 1
Summary lines = 1

Icon comment log.gif = Allg. Log
.....
Group SAP = .....

> Maybe it is a wrong configuration, because in this forum it works well.
> If I change the encoding in the logbook entry I get "Submit modified ELOG entry?",
> and after clicking OK the entry is closed. Because this behavior is on all loggbooks
> it must be a global config entry, but I dont know, which.
>
> ...
> Use Lock = 1
> ...

I comes from using the lock. If you remove that, you won't get this dialog box any more.

> > Maybe it is a wrong configuration, because in this forum it works well.
> > If I change the encoding in the logbook entry I get "Submit modified ELOG entry?",
> > and after clicking OK the entry is closed. Because this behavior is on all loggbooks
> > it must be a global config entry, but I dont know, which.
> >
> > ...
> > Use Lock = 1
> > ...
> 
> I comes from using the lock. If you remove that, you won't get this dialog box any more.
OK, it seems, that the last part of the Use Lock documentation is the explanation:
----
If someone edits an entry, but then goes away from that page or closes the browser without submitting the 
changes, a pop-up window appears asking the user to submit the changed entry. Although this works for most 
browsers in most cases, it could be that Javascript has been turned off in a browser, in which case the stale 
locks still might appear.
---
So if I switch the encoding the whole entry is reloaded, and the JS take it as leaving.
Is it possible to change this behavior? Changing encoding should be handled different as
"regular" leaving.

Additional information:
If you have set Use Lock = 1 you can't switch the encoding on a NEW entry.
The new entry is closed w/o saving. To prevent this you must input any data,
after them you can save the NEW entry with the PopUp-OK. But there can't be 
anyone else on a new entry?