If you would like to edit an existing pilot (to change or update authority numbers, customise the way your hours are totalled and so on) click the small person shaped icon next to your name. Note that if you have logbooks shared with you the icon will be different. Pilot details can only be edited from the account that owns the logbook so if the incorrect icon is displayed you may have to log in to another account to make changes.
Once you have clicked the icon you can make changes to your pilot setup. Please refer to the documentation for creating a pilot for further details on changing the settings for your logbook.