How do I Change the email for my Apple ID
How do you change the email associated with your Apple ID
MacBook Air
Question marked as
See the instructions in Change your Apple ID - Apple Support
and be sure to note the following from that link:
Before you change your Apple ID email address, you need to sign out of every Apple service and device that uses your Apple ID. If you want to use your iPhone, iPad, or iPod touch to change your Apple ID, stay signed in to your Apple ID on just that device.