Cannot get proper covers for some, not all files opening

[Robert987]

Hello, I have found that some books are not displaying covers at all while some have them inappropriately sized or otherwise problematic. Is there a way to fix this, possibly by downloading covers? Also, some files which I have been able to open with another e-reader do not open with this. Mostly they are not particularly exotic file types, just epub and pdf. In addition, I would like to be able to have books scroll horizontally rather than vertically. I thank you for your time making this reader available and am looking forward to your reply.