There are 2 ways to find your profile in order to update your information:
Click on your profile image in the bottom-left corner and click the "Profile"
Go to Setup > Account > Users > Your Named Profile and click the "Edit" button.
Your profile is where you'd go to change your login information (whether you log in using single sign-on, what your 2-factor authentication option is), your Notification settings, your Calendar settings, and your Outbound Email settings.