2) on that dashboard, check Users. See which of your usernames is the Admin of that blog. Let's call it blog A for Anonymous, and the new username you want to admin that, to be User A. Make sure User A is the admin. If it isn't, Invite it by email or username.

2) on your regular blog, check Users and see if User B is the admin of that blog. If not, Invite him to be. And then once he is the admin, you can delete User A from that blog. Same process on the other blog, in reverse.

Then you should have two separate blogs, A under user A and B under user B. Then you can change the privacy settings.