Why does my LG have white lines on it?

@febeobiechina all of this sounds like a bad display. It doesn't have to appear physically in order to have failed. I would start by replacing the display assembly.

There are no guides nor are there any YT videos for this model. You are going to have to use a guide like this which is for a slightly different model. The steps are most likely the same but the connectors and ribbon cables might be at different places etc, The actual display is available at multiple places online, just make sure that you get the right one for your version.

While you work on your phone, take lots of pictures. Once you are done with it, take those pictures and create a guide for iFixit. That will help the next person that has the same problem as you do. It's easy and fun to create these guides. https://ifixit.com/Guide/new The iFixit community will appreciate this.

Repair is War on Entropy!