How do you select a voice?!?!?

I click the icon to switch voices, which brings up a menu of (presumably) available voices. However, when I try to select one nothing happens. I can preview it. But it's completely unclear how to actually select it, so I can sue the voice. I feel like an idiot. It seems like selecting voices from the library of available options should be intuitive. I mean, that's a core function of the app, right? So why is it so hard? Am I really that dumb, ha ha ha

Please help. Point me to a tutorial or give me directions. I really want to like your app, but I need to be able to actually try the voices not just see a library of them and then not be able to do anything.