Click your name in the top right and choose My profile to view and change your own details.
Under Personal information, update your name, email address and a short bio. If your board has enabled phone number and address (see the privacy setting in Site settings), you can fill those in here too. Your instruments and band(s) are shown here for reference — those are set by a music or board manager, not by yourself; see Members.
Under Change password, enter your current password along with your new one (twice, to confirm). This works independently from the rest of your profile — you don't need to save your other details first.
Click your name in the top right and choose Log out at the bottom of the menu.