Can't change new apple-id (icloud) on my iphone

You are sign in here .  .  .  with your Apple ID & Password.

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

BUT now I can't change my new icloud / apple ID on my phone as it still give me my old email address.

See -> What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

See also the following Apple articles:

If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

Reset your Mac login password

https://support.apple.com/en-mn/guide/mac-help/mh35902/mac

If you forgot your user or account name on Mac

If you forgot your user or account name on Mac – Apple Support (UK)

Change the login password on Mac

https://support.apple.com/en-gb/guide/mac-help/mchlp1550/mac

Sign in with your Apple ID

Sign in with your Apple ID - Apple Support

If you forget your Apple ID or password

If you forget your Apple ID or password – Apple Support (UK)

I bought myself an Apple Macbook Pro 14

Enjoy your new purchase 👍