We just added the possibility for users to edit the title of their newspaper. When you are signed-in and on your newspaper, mousing over the title will show a pencil icon (confirming you can edit this title) –
Clicking on the title will then allow you to change it. You can Save to confirm your changes, or revert back to the default title.
Note that such editing is only possible for now on newspapers based on your own Twitter username or list.