Default [Q] Google Voice app setup help

Trying to enable Google Voice on my new M8 (running CM nightlies) for use with visual voicemail. However, when I do this, all SMS messages get sent with my Google Voice number and not my normal cell number. I figure I'm missing something but was hoping someone can point me in the right direction for setting up properly. Uninstalling the app resolves the issue immediately.

When I install the app, I'm given a settings page that I can't find after setup is complete, so I'm unable to go in and change those things. What the heck am I missing? I figure it's something stupid.