How to make my Iphone photos Private from other devices?

I have some photos that i'm not interested in my family seeing. I share an icloud account with my brother he changed the password and is not telling me. I made a new icloud account but whenever i try to do something it asks for my brothers accounts password.
On my settings my photo stream and photo sharing is turned off and under settings- icloud photos are turned off. Should i delete all my photos? There must be something i'm missing How can i prevent my pictures from being shared on other devices?

Lock the device, try Leo Privacy Guard