Why is my Apple ID setting greyed out on iPad?
I am running iOS 11.3 on my iPad. Recently, I have changed my Apple ID and password. Since then, when I go to SETTINGS on iPad, my Apple ID, iCloud, Messages, Face Time and iTunes & App Store settings are greyed out, so I can not change them. Why? What can I do to enable those settings?
When Messages prompts me to login, it shows my old email address associated with Apple Id, but I can not change it. Messages settings are greyed out.
Also, when I go to my account on Apple website, I see in Devices my Mac, MacBook and iPhone, but not iPad. Same thing, when I check my Devices on iPhone. My iPad is not visible. This is strange.
At the same time, on my iPhone (also iOS 11.3) and Mac (10.12.6) everything works as expected.
iPad 2 Wi-Fi, iOS 11.3