You asked [4 questions on Stack Overflow][1], not Super User. [One of those][2] was migrated here. 

There's no 'old account', just accounts on different sites catering to different audiences. 

  [1]: https://stackoverflow.com/users/2430839/jacky-zhou
  [2]: https://superuser.com/questions/614089/how-to-read-the-file-in-u-disk-copied-from-mac