@cullenga,
Sounds like the app isn't the greatest. I know there are any number of deficits with Facebook apps. E. g. I have a Lumia phone, and I can't change my commenting identity at all. You may need to make the commenting identity changes on your laptop or desktop and not on your phone, sorry.
PS App developers sometimes have forums or contact information. How about contacting the developer, if you can? Explain the situation. Perhaps there's a workaround or that's on the development agenda for the future. Or maybe they're unaware that it's a problem.