我有一个带有Android 4.2.2的LG G3。当电话响铃或当我收到邮件时，手电筒将打开。
I have LG G3 with Android 4.4.2. When the phone rings or when I get a message, the flashlight will turn on.
How to turn it off?
This setting should be found in
Settings -> Accessibility -> Flash alerts. It's primarily used to notify people who are hard of hearing about calls and messages.
Source: Sprint's LG G3 User Guide