How do I change my AppleID?

Change information in Apple ID - https://appleid.apple.com/

Change your Apple ID - "Follow these steps to change the email address that you use as your Apple ID." Plus special instructions if your Apple ID ends with @icloud.com, @me.com, or @mac.com

https://support.apple.com/HT202667

If you have problems:

Contact Apple for help with Apple ID account security - "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." https://support.apple.com/HT204169

You cannot change an Apple ID but you can create a new one and stop using the old one. However, you cannot transfer anything purchased under the old Apple ID to the new one. Only Apple can do that. You should not change an Apple ID just for convenience. Apple would prefer you have a solid reason for making such a change. You can make other changes such as your email address, password, etc. See below:

For Problems With Your Apple ID

1. Forgot iCloud Password
2. Forgot Apple ID
3. iForgot Password - Apple ID
4. Apple ID Password Change
5. iForgot UserName - Apple ID
6. Apple ID Name Change
7. Apple ID - Apple Support
8. Manage your Apple ID primary, rescue, alternate, and notification email addresses
9. About your Apple ID email addresses
10. Get help with Apple ID
11. Contact Apple for help with Apple ID account security - Apple Support
12. What to do after you change your Apple ID email address or password - Apple Support

Reset Security Questions

Contact Apple for help with Apple ID account security

You may need to reach Apple’s Account Security department. If you cannot find your country or are not able to call, then complete this form and send it to them.

There shouldn't be. See if this helps.

Apple ID Name Change

What to do after you change your Apple ID or password - Apple Support     I suggest doing this before you change your Apple ID or password.

Change information in Apple ID - https://appleid.apple.com/

Change your Apple ID - "Follow these steps to change the email address that you use as your Apple ID." Plus special instructions if your Apple ID ends with @icloud.com, @me.com, or @mac.com

https://support.apple.com/HT202667

If you have problems:

Contact Apple for help with Apple ID account security - "This article provides country-specific Apple Support contact information for customers seeking help with their Apple ID password or other security-related issues." https://support.apple.com/HT204169