Same problem here- I've been fighting it for months now. It wouldn't allow me to change it to NO ALARM- no matter how many times I changed the settings it kept defaulting back to 10 minutes. So I tried changing it to anything: I was able to change the alarm to 30 days, but not NO ALARM. Now that it's set at 30 days, I can't change it to anything else- not even back to 10 minutes.
This program is pretty terrible. I'm going to recommend that we switch to FileMaker Pro soon.