kindle

My wife's kindle app on her iPad Air2 is frozen on a book page and completely unresponsive. I decided to delete it and re-download from the App store but I can't delete it. Usually when I select and hold an app, a small x appears on its corner and I can the click on that and select Delete...

I have read how to change the font size and margins however even when I tap on the screen I do not have the "Aa" icon in the tool bar at the top, (only a brightness control, the notebook & flashcard icons). My iPad is an iPad 2, I have the latest iOS update and my Kindle app is fully updated...