Okay, let's take a deep breath and discuss a couple things.
1. Rooting is a very careful process where you need to have the utmost patience and diligence. If you do something wrong or miss a step, you can render your phone inoperable.
2. Google, the people who created the Android OS, have decided to deny apps access to the SD in all newer versions. This means that they cannot be moved or installed to the SD card without first rooting the device. This is normal and working as intended.
3. I would listen bg4m3r when he tells you to click the link and follow the directions carefully. you have to download the stock rom, flash your phone's rom back to V3, and then go from there. You cannot just buy an LG volt and root it out of the box, that's not possible these days. After flashing the rom with V3, then you can install Towelroot and SU.
As a quick side note, I received a replacement Volt from VM this week, currently flashing it back to V3 so I can root it and get rid of all the crap apps.