Permissions
 

I really can't get my head around this function.

No matter what I have tried, I am still struggling. As an unregistered user I am still able to edit another persons post.
This is the only permission at the moment I am trying to deny.

I want to go back to the beginning and revert all, but I have tried that and the headings in permissions still remain red.
I don't know if it is me who is fault or if it is the system.

I will persist. A guide would be useful.....

Thanks.........