Why does my sister's intials show up over my name when I log into AppleTV?
My initials are JW for my name, but my sister's, KO, initials show instead on mine.
iPhone 14 Pro, iOS 18
The Apple TV box, as well as the Apple TV app on third party devices, can have multiple user accounts. Just one of those accounts will be the active account at any time. Users can switch between them, so that each user can load their own watch progress and other account properties.
If the account has a profile image, then it will display that. (You can do so on e.g. icloud.com﹥Settings﹥Photo.)
If no account image has been set, then one or two initials will be used instead as icon, based on the name of the user account.