I just got an LG V30 and the file manager it comes with is a bit odd. If your home screen is setup like mine was you will see a folder called Management and in there is an app called File Manager.
On the upper left is a menu with three lines. Tap on that and you will be able to switch between internal storage and your SD card. First go to the SD card and create a folder (or multiple) to move your files to by tapping on the three dots menu on the upper right and choose new folder.
In internal storage tap on a folder that has files you want to move. Then tap on the three dots menu on the upper right and one of the choices is Move. Tap on that and it will put a check box next to each file in the folder. Check the ones you want to move and tap on MOVE in the lower right corner, then choose SD card. Choose the folder you want to move the files to and tap OK. If you're chicken you can copy the files the same way instead of moving and then delete the files after you're done.
If the files you want to move were put into internal storage by an app - like an ebook reader - you might be able to move them from there. Otherwise you will need to tell the app where to find the files after you move them using the file manager.
LG does allow you to move apps to the SD card. I can post screen shots later if you need me to. Not all apps allow you to move, but the Kindle app does allow it. Go to Apps in the settings menu and tap on the Kindle app. Then tap on storage and it will show it's currently in internal storage. Tap on change and choose SD card and it will move some of it to the SD.
I'm dyslexic and tried to make sure I said left when it was on the left, but if you don't see something on the side I said it was on try the other side!
