First off the online manual for the Fenix 5 is useless. It says there is an auto and manual mode but neither of those exist. They did on the Fenix 3, but not this one. There is a watch mode and an activity mode. Within those is no auto option I can find. The only option that kind of makes sense is in timeout section. Still if I set it to "no timeout" the light still goes out on its own. Typically after 15 seconds. Maybe I am missing something but for the life of me, I cannot find a way to keep the light on.
And for the record...I have owned many Garmin watches through the years including the Fenix series. I cannot understand why Garmin doesnt pay somebody that knows software. Every new model is like we are alpha testers which is crazy to me.
