Files restarting annotation and being extremely buggy

I have the latest Ipad Air and bought it solely because i trust that apple will not disappoint only to be shocked by how extremely buggy the entire device is especially when using the files app. When i have annotated alot of words for my school notes the app will suddenly return to the first page, deleting all the things i have written down. WHy is this?? This is so frustrating as i have to rewrite everything and not to mention how the pens do not change if i double tap sometimes. even the toolbar does not work. and my pens do not change or the eraser cannot be used. I also always have to start my strokes with a thick marker tool. Apple please fix this .

I am extremely frustrated after reading all the threads here that there is still no solution for this issue.