Back in zone heart rate alert

hello

I've read the instructions, played around in the menus and googled but I can’t seem to find the answer I want. Apologies if I’m missing something really obvious....

I've upgraded from an ancient forerunner (405?) to a fenix 5S. I do most of my runs using heart rate. I’m having trouble with the alerts. On the old forerunner it beeped when I went over my set heart rate but it made a different sound when I went back under the target into my correct zone. It was great because I didn’t have to keep looking at the watch. I can’t seem to find a way of doing this on the fenix. Am I being thick? I can see there is a low range alert but surely if I enable that the bloody thing will beep all the time?