Click on your username in the upper right-hand corner and choose "Account Settings" in the drop down menu.

Alternatively, click on your profile picture and choose the "Account Settings" button on the upper right side of your profile page. 

To change your display name (username):  Click the "Change" button to the right of the Display Name field or click "Display Name" in the menu on the left. Enter your new display name in the field and hit "save". (Please note that member names cannot be updated more than once every 30 days).

To change your email: Click the "Change" button to the right of the Email field or click "Email Address" in the menu on the left. Enter your new email address in the field and hit "save". Follow up by clicking on the activation link sent to you via email.

To change your password: Click the "Change" button to the right of the Password field or click "Password" in the menu on the left. Enter your old and new password where required and hit "save".