How to Customize LG G3 Built-in Icon PackHere are the easy to follow steps that let you do just that:
1. Long-press on an app until it is ready to move, a purple paintbrush icon will appear.
2. Lift up your finger and tap on the paintbrush to launch the icon edit.
3. Select one of the built-in alternative icons, or import one of your own. You can able to take a picture or use a file saved to your phone gallery.
That's it enjoy your new icons =)