There are two options for you to reset your password:
Option 1: Reset your password within ForeFlight Mobile. To do this, go to the MORE > ACCOUNTS. Tap on SIGN IN on the right side of the page (Near the bottom) and then enter your account email address in the EMAIL line. Once you have done that, tap on the FORGOT PASSWORD? button. A new temporary password will be emailed to the email address you entered.
Image 1. MORE > ACCOUNTS > SIGN IN
Image 2. Enter Email address and select FORGOT PASSWORD?
OPTION 2: Reset your password using ForeFlight on the web. To do this, go to the ForeFlight Website. Enter your ForeFlight account email address and then click FORGOT YOUR PASSWORD. A new, temporary password will be sent to the email you provided.