Your boards
Every board you create or open in this browser is listed here automatically, with how long each one has left before it is deleted.
Saved in this browser only
This is not an account. Clearing your browser cache or site data wipes this list, and a board with no link is unreachable forever. The boards keep running on the server, you just lose the only record of where they are.
Board passwords are kept separately in this browser in plain text. They are never written to the export file, so store them somewhere of your own as well.