For some reason I can't disable guestposts within settings_misc.php. What to do? Are some php files corrupt, or do I have to alter the DB, and if so: where?
I think You are looking at the cell content and its conditions, as you posted earlier. You are not looking at the actual DATA. If You look properly You should see that there.
Look at this... Structure is selected, slightly darker grey:
and then You select BROWSE:
When You browse, you should be able to see a small EDIT (the PEN):
And then lastly you should change "0" to "1":
lastly go to the bottom of the page and hit GO on Your right, as in making the wanted changes.