Apple TV Sign In
Why do I have to sign into Apple TV every time I go to use it?
Are you accessing the Apple TV+ app from a TV?
If that is the case, I would assume your TV is not saving login settings for the Apple TV app. Depending on the manufacturer, some have a privacy setting that prevents an App from saving any data to the device. Other times there is a Privacy statement you must agree to on the TV before the app can save any data. Let us know what TV you have and we may be able to help further.
If you are talking about the Apple TV set-top box, please specify as that would be a completely different issue.