I find the alert volume too quiet also. This is a replacement for a Forerunner for me. I had no issues with the volume of the alert on that unit, but last night out running I missed lap notifications for my interval training - in spite of the vibration alert.
I think the alert functionality has not been updated by Garmin in many years - it is the same as it was in an Edge 500. I posted years ago a suggestion (as did others) that Garmin allow a user to select different alert sounds and volume so that one can differentiate between alerts without having to look at the unit (watch/bike computer/etc) A simple enhancement with significant impact to to usability.
