In some games, specially driving games, there is a setting to either use screen buttons or the gyroscope and i find that manual control actually works better. Make sure you are playing with the right settings.
If you want to check the sensor is working or not, there are tons of apps on play store to do that, CPU-X or CPU-Z for example.
Watching VR is bad because just having gyro isn't the only thing that matters.
The phone also needs to have a high resolution display. At the least 1080p, because the video is actually splitted in to half the resolution, which means if your phone has a FHD display, you'll get 540p output and if
QHD display, then 720p output.