Can't change my (wrong) email address
Please note: I didn't tested this but it is the only place where I found an entry to change your mail-address
Go to vivaldi.net --> login --> than click on your nickname in the upper right corner --> a popup appears which has a pencil symbol on the right side of your profile pic - click this than you'll get redirected to your account settings where you can change your mail-addy
You cant change it currently. the mail address is used internally as login data in webserver. The webadmins will change this in future.
if you need to change the mail address please send a mail to firstname.lastname@example.org