Hi Stacie,
I assume you mean PDF? The nature of PDF means it is a fixed page layout - you see exactly what the author intended.
You can use the free Calibre software to convert the PDFs to a more suitable format like EPUB. The software runs on Windows, Mac and Linux.
The quality of the conversion will depend on how the PDF is formatted - I've found that it's usually good, but
sometimes the ends of lines come where you
least
expect them. Have a go and see if it works for you.
Hope that helps
T