Can I change the email address on my account?

Yes, in Settings and then Profile. Changing it sends a confirmation to the new address, and the change takes effect once that is confirmed, so a mistyped address cannot lock you out of your own account.

The address is your identity here: it is what you sign in with, where password resets go and where account emails arrive. Billing documents can go somewhere else, so an accountant can receive invoices without having access to the product.

If you use Sign in with Google, keep the two addresses aligned. The account is resolved by email address, so changing one without the other is how people end up with a second empty account.