Hi, I've been having this problem for a bit now. I have an LG G Vista and it has 8 GB of storage. So I bought an SD Card but when I try to install apps, I get the "insufficient storage space" message. I have pressed "move to sd" but it won't move the entire app. So now I can't download apps or use my SD card as storage. I would like an answer that doesn't involve ''unlocking" or "rooting" my phone if possible. Thanks.
Actually, if you are using an OS below Marshmallow, that option isn't there. Also, Samsung has limited the ability to run things from SD Cards on some phones. Why, can't say, but they have. The only way to know for sure if your phone will allow it, is to use a blank card (as this will erase anything on it), and see if your phone will allow setting the card as "Internal" rather than the standard "External". If it will, your are good.