It is easy to capture screen on LG G Flex. Just press and hold the Volume DOWN key and Power Key at the same time, You can take a screenshot on the LG G Flex.
But, Is it annoying that the screenshot includes the status bad and front touch buttons?
The G Flex’s “Screen Capture Area” feature allows you to exclude the the status bar when you take a screenshot.
How to captures the screen excluding the status bar on LG G flex:
Go Setting → Screen → Screen Capture Area → Select ‘CapturePart Screen’
Now, press and hold the Volume DOWN key and Power Key at the same time, You will have the screenshot without status bar.
Wish this Helps!