To reset your password, please visit the login screen in the app after inputting your email address. Look for a link that says "FORGOT PASSWORD".
If you use the password reset link directly, make sure to select the "SEND EMAIL" button on the password reset page only once. The reset emails will expire if you request it multiple times within a short period.
Alternatively, you can visit this URL directly.
If you are still having problems, please make sure the Date and Time setting on your phone is set to Update Automatically.