Thanks Sunny for your reply. Tested again and noticed:
- With my Galaxy Note 8.0. There are icons for front and rear halves at top-right corner. No matter which icon was touched, only front cam was shown.
- With my iphone 5s, there is one icon for the live view, when the video is being shown and screen is touched, there is icon to switch between front and rear camera and it worked fine; it even remembered the last chosen camera and would show video from that camera when live view was selected.
- Connection seems to be faster more stable with iphone 5s than that of Note 8.0.
- Lukas app on the iphone 5s allows screen rotation while the app on Note 8.0 doesn't.
- V-OUT function, I couldn't find any option in LUKAS Setting that allow to select video output from front or rear camera, only V-OUT from front camera as default.
- All the settings will be reset to factory setting (language, wifi id and password, etc.) once the dashcam is disconnected from power supply.
So I guess it's Lukas App (for Android) bugs for point No. 1; new version of Lukas App may address issues mentioned in points No. 3, 4; and new firmware may support V-OUT for the rear cam (point No. 5) should the hardware support it.