[Koha] "Unlocking" the 100$a cataloging-field

[le-grex]

Me again, hello,

i try to add a own framework for our needs here, since almost nobody 
knows about the MARC Things and so on and i want to make it easier for 
them. But the 100$a authors field is locked, i can't fill something in.

So i went to Administration, System Parameters, and changed 
BiblioAddsAuthorities to "should". But it is still locked.

Is there a second location, where i need to change something?

Thank you again.

grex