If you want to give your device a new identity by changing your device name just follow the steps

• Open the Terminal (Ctrl+alt+t).
  
• Write gksudo gedit /etc/hostname and press enter.
• Put the Administrative password and click on OK button.
• You can see current device name in hostname file. Rename it with your new device name.
• Save(Ctrl+s) the hostname file.
  

  Change device name in hostname file

• If any other Document like Untitled Document 1 will open and want to save at the time of closing you can choose Close without Saving.

Try it yourself.