This app lets you change the G4 volume up shortcut. I'll probably use it for flashlight shortcut when I get my G4.
Key Plus - Change LG G4 Volume key shortcuts… | LG G4 | XDA Forums
Sent from my LG G2 running CM 12
Key Plus - Change LG G4 Volume key shortcuts… | LG G4 | XDA Forums
Sent from my LG G2 running CM 12