You can change your password on Fatsoma as many times as you like and any changes will take effect straight away.
To change your password:
Sign out of your Fatsoma account at fatsoma.com
Enter your email address and submit
Click the link sent to your email address
Enter your new password
Please note that the forgot password page is only accessible when you are signed out of your account, so make sure you sign out before following the steps above.
As a general tip, it's always a good idea to use a unique password for every website you use to keep your account as secure as possible.