Elasped Time Data Field

When I go on a hike, I have Elasped Time as one of my data fields. And I've also tried just regular Timer.  I want to know how long I've been on my hike. But after an hour or so, the field will reset to zero and start over. I did not press any button to make this happen. It's as if I'm hitting a button to insert a lap, but I am not. I saw a feature on Settings called Auto Lap, and it is set to Off (manual only). So how can I have the timer show the total time of the hike without resetting to zero? Thanks.