If you've forgotten your password, you can reset your password through the login screen within the app. Click the menu at the top left and select "Login." Then click the link at the bottom that says "Forgot Password." You will be prompted to enter the same email address you used to sign up for the account and then you will receive a link to reset your password.
If you do not see the "Forgot Password" link, be sure you have updated to the latest version of the app.