If I'm reading your dilemma clearly it seems like you are trying to record the game and your voice in the same program which I wouldn't recommend. I don't use an Elgato personally since I own an HDPVR but I would suggest using Audacity, a free program used for recording voice from mics like yours, to record your commentary separately and the elgato to only record the game, that's what I do at least. It's easier in editing to have two different files for your commentary audio and your game video/audio to make sure that one doesn't over power the other.
Hope this helps you out.
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