A long-requested feature by members of the Twitch community has now become a reality: Twitch now lets users change username.
Yesterday, Twitch announced the new feature via its blog, telling users that they can now change their username once every 60 days. To make the change, users have to go to Profile Settings, see if they are elegible to make the change and then edit their current username to a new one.
After the change is made, “the abandoned username will be held by Twitch for a minimum of six months.”
One risk of making the change right now is that users of the service may lose access to their account’s stats. Twitch suggests exporting the stats under your current username before changing it to a new username. Old usernames may be recycled. Since January 29th, Twitch started reclaiming inactive accounts to make them available for other users.
Something else to consider is that after changing your old username to a new one, the old one will not redirect users to the new one.
[Source]: Twitch Blog: The hype is real: Name changes are here.