Unfortunately you can not go to idle screen during time measurement by stop-watch. The back button serves as lap button, so there is no way how to return back to idle screen.
However you can use hot-keys and get to functions hot-key offers as well as controls (long press of power button) and all functions controls offer. When you use those functions stopwatch is normally running on background however when you leave those functions (by back button) you will get back to stop-watch.
If you need to see time during stopwatch the only way is to set world-time to hotkey or via controls and you can see current time during stopwatch... however quite indirect solution. Alternative you could use activity function instead of stopwatch (configure some activity not to use GPS, to save power and use only Timer function there.
Hi. Can I ask why the elevation changed so much at 25:07?