I'd like to change the email associated with my account
You can update the email associated with your account at any time by going to your email settings page. Just click "Add another email", and then remove the old one.
I currently log in with Google, Facebook, or Apple, but I'd like to log in with my email.
No problem! All you have to do is go to your email settings page and add the email you'd like to log in with. Then, go to your password settings page and set a new password. After that, you should be able to log in with your new email and password. If you want to be safe, you could always test this new login in a private window to make sure it worked as intended.
Additionally, if you'd like to remove the ability to log in with your Google, Facebook, or Apple account, you can do so from your general account settings.
I currently log in with my email, but I'd like to log in with Google, Facebook, or Apple
Sure! You can add a third-party account login at any time by clicking one of the "Add a third party account" buttons in your general account settings.