You can do all of this by logging into your Roku account via https://my.roku.com. Click on the purple "Update" button under Account Information to go to the page shown in this image:

Changing the email address will also update the email address you enter to log into your account, as well as the email address shown for your account on the Roku.
Roku Community Streaming Expert
I am not a Roku employee, only a user like you.
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