How to update Apple ID on my iPhone?
How do I update my mobile ID on my phone?
[Re-Titled by Moderator]
If you haven't already, sign out of your Apple ID in the settings for iCloud and sign in again with the correct details:
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If you’re using iOS 10.3 or later, go to Settings > [your name]. If you’re using iOS 10.2 or earlier, go to Settings > iCloud.
- If you're signed out, enter your updated Apple ID and password. The data in iCloud will automatically appear on your device after you sign in.
- If you're still signed in with your previous Apple ID:
- Scroll down and tap Sign Out, then follow the onscreen steps. You might need to enter your password. Your data will remain in iCloud and will be updated on your device when you sign in to iCloud again.
- Enter your updated Apple ID and password.
If you updated your Apple ID email address* before signing out of iCloud, and your device repeatedly asks for the password to your previous Apple ID, you can temporarily change your Apple ID to sign in.
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copied from: What to do after you change your Apple ID or password - Apple Support