Chapter 10 Install and System Administration for FortiOS 5.0 : Basic Administration : Passwords
  
Passwords
The FortiGate unit ships with a default admin account that has no password. You will want to apply a password to prevent anyone from logging into the FortiGate unit and changing configuration options.
To change the administrator password - web-based manager
1. Go to System > Admin > Administrators.
2. Select the admin account and select Change Password.
3. Enter a new password and select OK.
Set the admin password - CLI
config system admin
edit admin
set password <admin_password>
end
See Also
Password considerations
Password policy
Forgotten password?