Hi Anne,
Welcome to wikitree, there will be people who can give you much better answers than this but in completely simple terms;
You can mark living people, and any profiles living people may still have a common relationship with as private when you edit them.
I had a quick look at the age of the profiles you've added so far (quick work by the way!), profiles over 100 years old we would recommend you keep as public.
No-one will edit your profiles without your permission as an active profile manager.
The reason profiles of this age are public is because the mission of wikitree is to connect everyone on 1 family tree!! We are all connected somehow!
I've merged some of my X x great grandparents because I've connected to others trees. Only one profile can exist for one person, if that makes sense?
Hope that helps, Lizzie