iCloud section on iCloud - definitive answer please!

I’ve tried recently to get an answer to the following question but simply haven’t got an answer. Can anyone offer a response?

On my Apple TV HD (under Accounts & Users), each profile shows login lines for iCloud, Store and Game Center. The iCloud line is greyed out for every user. All other lines are amendable/accessible.

Is this right? Should I be able to go into this line for iCloud to amend? If so, any ideas how I sort this issue out?