This article covers two scenarios - firstly when you have forgotten your password, and secondly when you need to change a known password.
From the login screen, https://app.caterbook.net/login click Forgot Password
Then, enter your Account ID and your username on the next screen.
This will send an email to the email address associated with your account.
On clicking the link in the email, you will be able to enter a new password.
Change a known Password
You can change your existing known password when logged in at any time from your Profile under Settings in the menu.