Movie Maker audio

I'm an "oldie" who has successfully used Movie Maker for many years to compose DVDs of holidays, grandchildren etc., combining video and stills and adding music. I was always disappointed at the lack of facility to "dub" my own commentary when suitable so was pleased to see the Narration facility when I updated to Essentials 2012.  I have a Logitech C270 webcam but am totally frustrated because I get no sound when I add webcam video to a project (silent video only). I'm similarly frustrated because I get no sound using the Narration tool.  The webcam mike works as I get audio when used in other programmes.  I can't find any audio settings within Movie Maker other than the standard volume and fade controls. Help!