ive forgotten my password to be able to change my Apple ID and email address. how can I change these?

You are sign in here .  .  .  with your Apple ID. & Password (?)

Your Apple ID is the personal account you use with all Apple products and services. It includes the email address and password you use to sign in, as well as the contact, payment, and security details that you use with Apple.

You can’t merge multiple Apple ID accounts.

Have you forgotten your password? -> See this Apple article: If you forgot your Apple ID password

If you forgot your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

See this Apple article: Change your Apple ID

Change your Apple ID - Apple Support (SG)