On older Android firmware versions, the System Default is selected by default, and sound options can be chosen within the app. Caution: If another sound is selected, it will not be possible to revert ...On older Android firmware versions, the System Default is selected by default, and sound options can be chosen within the app. Caution: If another sound is selected, it will not be possible to revert back to the default siren sound without clearing all Alarm.com app data on the device or uninstalling and reinstalling the app. If the app data has to be cleared, verify that the push device and Geo-Device settings are still configured properly.