To fix low volume in Nvidia Shadowplay recordings, open the game you are going to record, minimize it, right click your audio icon, open volume mixer, scroll to the right until you see NVIDIA Capture Server and the game. Set both to 100 percent and turn your volume up to 100%. Control the volume of your speakers or headphones with an in-line volume control. The PC must have volume set at 100% to record at full volume.