After the update from 5.2.2 to 6.4.3 there is a "Register" button in den log in screen. All ppl now can register itself, although I disabled this in versin 5.2.2.

After looking around, there is nothing checked in the new settings of 6.4.3. If I disable this for everybody (only admins ...) there will be only the login button.

This is not good.