"Period is late" button ??

For the life of me I can't find this button that everyone seems to be talking about, I've installed and uninstalled the app and all I see is a button that lets me modify my period, which will let me delete the days it projected it. It then shows me a new expected period. I'm on cycle day 40. Im new to glow, first month was great but now with a late period and a bunch of negative tests, I don't know how to use it because I don't know if I'm ovulating or not. Help!