its basically pretty easy. i had this problem but i solved it in few seconds.
basically you have the magnetic cover of the astro headset. First you need to remove ur microphone then u need to switch the outside magnetic cover ( the one with the microphone hole in it. Just switch those over and ur good to go. ull notice that the astro has 2 microphone hole on both sides. and voila problem solved. Hope I could help !! cheers