I don't think you can do everything through the app (such as post in the Community) like you can when you're on the site. If you're constantly having to log in when you're on the site, try clearing the cache and cookies on your computer to see if that fixes the problem.
"You may have a fresh start any moment you choose, for this thing that we call "failure" is not the falling down but the staying down." Mary Pickford
"No matter how slow you go, you are still lapping everybody on the couch."