stop File Check emails

Hi
I wanted to stop receiving emails like this from the plugin:
Subject: [NinjaFirewall] Alert: File Check detection
Message: NinjaFirewall detected that changes were made to your files.
…

So I have already checked the option “No (default)”
under Monitoring / File check / Options / Enable scheduled scans
but it continue to send me one message every day.
What can I do?
thanks