Ideally a video would show us how you are moving the sensors/zumo and how far from the line you are holding them, what the line you are testing with looks like, and if there are other environmental factors that might have an effect, but we would just not think to ask about.
If you are not able to post a video though, please post pictures that show the solder joints on the sensor array and front expansion area as well as how the sensor is connected to the Zumo. Could you measure the voltage of your LiPo battery? Just putting your hand over the sensor is not a great test. Could you try moving the Zumo over a black line on a white board or white paper while you run the qtr raw values example? Please post pictures of that too.