Security
Security puts a password in front of the Settings, so casual users at a club can't change decoder, sound or scoring configuration by accident.
When security is enabled you set a password. From that point on, opening Settings prompts for it, and the settings stay locked until the correct password is entered. Running events, race control and results are unaffected — only access to configuration is gated.
To turn security off again, open Settings (entering the password) and disable it.
Don't lose the password
There's no self-service reset — the password protects the same screen you'd use to change it. Store it somewhere the club committee can find it, and if it's lost, contact support.