To change your password or email address for login please click on your name on the top right-hand corner of the page after logging in and go to Settings.
Here you can change your name and last name as well as your company name and profile picture.
Email address and Password
Go to the account and billing section, it looks like a credit card symbol on the left hand pane.
Here you can change the email address used for logging in and your password. For the latter you will first need to enter the current password and click on Validate. You should then be able to enter a new password and confirm it to change the login credentials.