How can I stop my iPad from crashing the documents?

Why my documents get automatically crashed when I try to open a 50-100mb file , it again takes me back to first page when I scroll down ,and I have tried opening closing the app, my iPad is up to date and I also tried deleting the app but still it is crashing my ducoments. I am unable to study , what should I do?

[Re-Titled by Moderator]