Just to confirm, have you tried these steps to change your channel art here: https://goo.gl/f8Bx5n ? Keep us posted.
You can add location information to your Tweets, such as your city or precise location, from the web and via third-party applications. You always have the option to delete your Tweet location history. Learn more
Just to confirm, have you tried these steps to change your channel art here: https://goo.gl/f8Bx5n ? Keep us posted.