how can i change my phone number from finding my phone to e mail to get the verification code

Just to be clear ... your Apple 2FA Code "pop up" will ALWAYS be sent to all of your "Trusted Devices."

Changing your "Trusted Numbers" will not alter that function.

Additionally "Trusted Numbers" can ONLY be voice or SMS numbers, NOT an e-mail.

Your "Trusted Numbers" are additional voice or SMS lines where you can optionally have your codes sent on a case-by-case basis.

(i.e. when you don't have access to ANY of your trusted devices"

If you want to change your trusted phone number, which is the number you receive your 2 Factor Authentication codes when you sign in with your Apple ID, do the following;

Go to:

Settings -> Apple ID (Your Name) -> Password & Security.

Under Trusted Phone Number, press edit and add your new phone number. If you do not use the old number anymore, you can delete it when your new number is added.