LG K4 User Manual page 24

A touch screen failure may occur if you use the device near a magnetic,
metallic or conductive material.
If you use the device under bright lights, such as direct sunlight, the
screen may not be visible, depending on your position. Use the device
in a shady location or a location with an ambient light that is not too
bright and bright enough to read books.
Do not press the screen with excessive force.
Gently tap with your fingertip on the option you want.
Touch control may not work properly if you tap while wearing a glove or
by using the tip of your fingernail.
Touch control may not work properly if the screen is moist or wet.
or accessory is attached to the device.
Basic Functions 23