Weak security combined with poor service = terrible app

I was persuaded to download the app by American Express so that I could benefit from their Lifestyle Rewards programme. What a waste of time! People need to know that if you download the app on an Android device, there is no way to logout and if you close the app and then open it later, it doesn't ask you to login again using your private username and password. So, in effect, the app is always available to anyone who might use your phone - big problem if you should lose your phone. Added to that, I can't use the points as the app doesn't recognise them as part of my balance. I did send an enquiry to the support email address but that was a week ago and I'm still waiting for a reply.