There should be separate options to change/update passwords. Change/update name. And change and update email because that option is not there the option to change your email is not there.
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.