Hey, so a couple of months ago, my bro lent me his iPhone since mine had issue. I changed the apple ID on the device so I was able to access my keychain...along with his keychain. Which means when I go to a website I can choose to log in as him since the password would be pre-filled for me (both iphone and MacBook air). Now that the iphone has been returned to him, I wonder whether he could log in to website as me also? Is there a way to make sure only my devices are able to use the keychain or have my password pre-filled? Should I just erase keychain and rebuild?