android app not working correctly

I just purchased a new phone and when I open the android app it will not allow me to interact with it. It will unfreeze at times and then lock back. I know my old phone used Android 8 and my new one is using 9. Is there something I can do to correct this. I am an ultimate user but not having access to my schedule while on the go will make me search for a new app. I do not want to do that.