I have run into this problem in the past, but forgot how to resolve it.
I am running LO 184.108.40.206 on Linux. I have just installed a new printer,
an Alps MD-1000 color printer. I created a document with an inserted
image in color in OpenOffice and I am having a problem printing it at
1200x600 there, so I figured I would try it in LibreOffice to see if it
has the same problem. The document opens fine in LO, but when I try to
print it using Ctrl-P, selecting the MD-1000 printer and then
"properties", the "Paper" tab options are all greyed out and
unchangeable. This was not happening in OpenOffice. Note that the
"Device" tab options are not greyed out.
The only work-around to a similar problem I have notes on is to select
the paper size in Format > Page, but that is not a solution in this
case, since the printer print dialog Paper options include more options
than just paper size. They include the DPI resolution also. These are
not options in the Format > Page dialog.
What is the solution to get these options back again?