The Change Password setting allows you to change the password for the User you're currently logged in as. You'll need to know your current password to do this.

To access this, click your username on the top right and click change password.

Enter your old/current password, followed by your new password twice, and click Change Password.

The new password must be at least 8 characters long, and contain a mix of upper and lower case letters, numbers and special characters.