How can I set defaults on zap config?

When I configure a zap extension, it generates a line in the zapata_additional.conf file that reads:

echocancel=yes

However I don’t see such as line in the web nor a place to reset it. Since I don’t have echocancel hardware, this causes my extention to be inoperative until I manually set it to “no”.

Where do I set this to cause it to default correcly?

Thanks,
Jim.