You can edit your profile using the Admin Toolbar. After login, you can edit your user profile by clicking on your name in the top left-hand corner, then click Edit profile.  

Alternatively, you can click the Edit tab if you are on the default page when you first log in to your website.

From the “Edit profile” screen, you can update your email address, username or password.  There is a lot more on this page however, you only need to worry about your Email, Username, and Password.   

Whichever way you choose to make changes to your User Profile, make sure to click "Save" at the bottom of the page when you have completed making your edits.