I had my LG G3 rooted before I updated after the update it says I'm still rooted but xposed and titanium backup and su cant get root access. I am new at this so any help would be appreciated.
You have to take it all the way back to the old OS using the LG Flash Tool. I just did mine last night and now it's running The LiquidSmoth ROM flawlessly.
I have the LG G3 on ATT running Lollipop. Im sorry to say, that there currently is not root method for the Lollipop version. If you are willling to wait, a root method may come out in a few months. If not, use LG FlashTool to downgrade and flash a custom rom. I didnt have the patience to wait, so i installed CyanogenMod 12.