How do I change my phone number in Google for account verification?

From any Google page (eg: email, drive, classroom), click on the profile circle with initial, photo, emoji at the upper right corner of the screen

Click the Manage your Google Account button.

Open the Security tab on the left side of the screen (sometimes found on the top when using a phone).

Find How you sign in to Google and look for 2-Step Verification phones.

Click arrow to the right to find the phone number(s) listed for authentication.

You must add a new number before removing the old one.

Google will send a verification message to the new phone to confirm.