When you login with one-time code we don't have access to your keys - so we use our keys to create a site for you. But some features require access to your keys - that's why you can't change them. There should be a "Connect keys" menu option in dashboard, it will ask you to import your nsec into nsec.app, connect it to npub.pro, and migrate your site to your keys. You'll have full-featured access after that. Does it make sense?