The default cPanel username is set as the first 8 letters of the primary domain for the account. It is possible to change the username on your account, but we strongly recommend to reconsider that. The reason is that the cPanel username is linked to a large amount of services and the actual change is an unpredictable process that can completely corrupt your hosting account and all websites on it. We do not take responsibility for the outcome so if you wish to move forward with it, this can only be performed after a confirmation that you are aware of the damage it may cause.