Changing the email address used for my Apple ID
The instructions on Apple's support website (https://support.apple.com/en-us/HT202667) seems out of date. I changed my apple id from a third-party email address to my iCloud email address on my iMac WITHOUT first signing out of all my devices (iPhone, iPad and two Apple TVs). After the change, all of my devices and MacBook Pro magically (automatically?) changed to my updated apple id. What am I missing? What horrible pitfalls will I encounter? I assume it may have worked seamlessly because my iCloud email was already listed in the "reachable at" list of email addresses?
iMac 21.5", 10.14