How do I change my Apple Account and password?

Have a look at the related articles, explaining all steps:

Change your Apple Account password - Apple Support

Change your Apple Account primary email address - Apple Support

Go to https://iforgot.apple.com.

The support article Change your Apple Account primary email address - Apple Support outlines various methods for changing the email address (Apple ID) you use for your Apple Account while retaining everything in your account.

Exactly how you change your password depends upon if this is an adult or a child, and the equipment you have. Click on this link to learn how to change your Apple ID password --> Change your Apple Account password - Apple Support

If you have forgotten either of these, this article tells you the various ways you can try to discover your forgotten Apple ID --> If you forgot your Apple Account primary email address or phone number - Apple Support Typically an Apple ID is an email address you have used. If you are currently using a mobile device that is logged into your account, go to Settings and tap your name at the top. Look in Keychain, and in a browser's security settings if you use it to automatically sign into Apple when using a browser.

This article outlines what to do If you forgot your Apple ID password --> If you forgot your Apple Account password - Apple Support

or go directly to this link --> http://iforgot.apple.com/

If you find you can’t sign in, reset your password, or receive verification codes, you can request account recovery (read this support article: How to use account recovery when you can’t reset your Apple Account password - Apple Support ) to regain access to your account. Account recovery might take a few days or longer, depending on the specific account information you can provide to verify your identity. More detail in —> Activation Lockout Issues - Apple Community

If you still need help this page provides country-specific Apple Support contact information ➞ Contact Apple Support - Apple Support