I have LibreOffice 5.0.2 (Writer) and when I try to print or export my document to PDF, the page width is too wide on the output. The document is set for US Letter (default settings), and it shows up correctly when editing and if I use File >> Print Preview. However, if I go to print, the preview has the correct aspect ratio for the page, but the text acts as if the page is much smaller, and in particular, too narrow. If I export to PDF, the PDF claims that that page size is 8.5 x 11 inches and the aspect ratio of the page does look about right, but the text on the page acts like the page is much smaller, exactly like the print dialog.
In fact, it looks about like it might if the page size were A4, but adjusted to fit US Letter. I was in China for a few years, so it is possible that I set the defaults to A4 in LibreOffice and/or OpenOffice.org before I upgraded to LibreOffice. (Is there any way to delete whatever saved settings there might be?)
My language settings are English US. I am using OS X Yosemite 10.10.5, English, but I have Chinese input methods enabled. This problem also happened on LibreOffice 4.x (forgot to record the exact version before I downloaded 5.0.2 tonight to see if it had been fixed).
Even a workaround would be good, since LibreOffice Writer is pretty much unusable with incorrect page margins.