Question

Where can I change my registration? When registering, it asks for a phone number, and when you log in the email?

Answer 1

I've registered on the website of OttPlayer and indeed it asks for the phone number if you have defined one which represents another way to login. However, the first time you log in with the email address and then add the phone number if you want.

They show a notification after a successful login that you should add a phone number in order to receive notifications.