Welcome to the forums, Ozarka.! As it stands, since "Lui" is currently in-use by another Ubisoft account, it won't be possible for Ubisoft Support members to change your username to this exact name. However, if there are any alternative names you'd like to use instead that are not in-use by another Ubisoft account, this will be something our teams will be happy to assist you with via the Support website.