Keep in mind you can also use different Apple ID accounts at the same time for iCloud and iTunes/App Store. The entry would change to Sign In after successful logout. Note: You can add an app to the TV's Home screen by going to Apps, selecting the Settings icon in the upper right corner, highlighting your desired app, and then selecting Add to Home.
There are a variety of reasons you may need to change the Apple ID you’re using with the iTunes and App Store. In the Mac App Store Menu bar, go to Store Sign Out to sign out. If the app isn't listed on the Home menu, use the directional pad to select Apps, and then select the app you want. Need to permanently or temporarily change the account you’re using for the iTunes and App Store? Follow along for how to change your iTunes and App Store Apple ID on iPhone.
