How do I add existing iPhone to new Apple Account?

In February, 2025 Apple started allowing purchases to be migrated to a different account. This is not available in all countries. If you do wish to migrate purchases, Apple has several lengthy and detailed articles about doing this, including limitations:

- If purchases made in a secondary account can be migrated to a primary Apple Account to consolidate them. (This feature isn’t available to users in India.) —> Migrate purchases from one Apple Account to another Apple Account - Apple Support

- Learn about what purchases and associated content can be migrated between two accounts. —> About migrating Apple Account purchases between accounts - Apple Support

Sign out of the first account on the phone you want to change and then sign in with the new account on that device. Understand that anything downloaded to that device with the old Apple Account is locked to that account. You would need the old account username and password to update apps, etc. The easiest thing is to delete the apps from the old account and just download them again with the new account.

On the one iPhone you want to setup with the new Apple Account, go to Settings > General > Transfer or Reset iPhone > Erase all Content and Settings. This will bring your iPhone to factory settings and removing Activation Lock, then you can go through the setup process and sign in with your new Apple Account.

But if you want to preserve settings and apps, go to Settings > [your name] > Scroll down to Sign Out.

Thank you for that information.