The support article Change your Apple ID - Apple Support outlines various methods for changing the email address (Apple ID) you use for your Apple Account while retaining everything in your account.
If you have an iPhone or iPad:
1. Go to Settings, then tap your name.
2. Tap Sign In & Security.
3. Next to Email & Phone Numbers, tap Edit.
4. Tap the Remove button next to the email address, then tap Delete.
5. Tap Choose Another Email Address and enter your device passcode if asked.
6. Enter the new email address, then tap Continue.
7. Enter the verification code that was sent to your new email address. Read this support article to learn what to do if you didn’t get the email —> If you didn't receive your verification or reset email - Apple Support
8. If you encounter issues with certain services after doing this, this outdated support article may still have useful suggestions --> What to do after you change your Apple ID or password - Apple Support
Refer to the support article Change your Apple ID - Apple Support :
- If you don’t have an iPhone or iPad the support article says to, “go to https://appleid.apple.com and sign in. Then follow the onscreen instructions to change the email address associated with your Apple ID.”
- For general information, and other issues such as changes or addresses not being accepted.
- Note a recent change to the article where you can now change the email address without having to have access to your old email account.
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Check iMessage and FaceTime settings for your device. On an iPhone or iPad go to Settings > Messages > Send & Receive, and make sure both your telephone number and Apple ID are input there and both show a checkmark. If you need more help, check out this link: Add or remove your phone number in Messages or FaceTime --> Add or remove your phone number in Messages or FaceTime - Apple Support
Check your Siri settings to make sure your correct contact information is selected. You can do this by going to Settings > Siri & Search, and making sure that My Information shows your contact card information. If not, tap on it and select your correct contact card information from Contacts. See also: Tell Siri about yourself on iPhone - Apple Support. Tell Siri about yourself on iPhone - Apple Support
Ref. family sharing confusion - Apple Community
To edit your list of trusted items go to the section: About trusted phone numbers and trusted devices in the document Two-factor authentication for Apple ID - Apple Support