How do I change my email address?

On the website, go to Dashboard → Profile → Email Address and tap Change. You'll confirm twice: a code sent to your current address first, then a code sent to the new one. Everything on your account (Pro, study history, program records) comes with you.

I can no longer open my old email

Email [email protected] from the new address and tell us the old one. We'll verify you another way and move the account.

My instructor invited a different email than the one I use

Don't create a second account. Either change your email here to match the invitation, or ask your instructor to cancel the invitation and re-send it to the address you actually use. See How do I join my program?

Does this change where my codes go?

Yes. Login codes and account notices go to the new address immediately after the change completes.