Why is "Page tray" setting not available to me?

When I open the Format > Page > window and click on the Page tab, there is a Page tray setting box. However, the only option listed is “[From printer settings]”.
I have tried several things in both LibreOffice and in the printer settings to make it possible to set the printer tray, but to no avail.
I am using an iMac with OS X 10.10.2 (Yosemite), and LibreOffice, and want to set an English Writer document to print from the auxiliary (secondary) tray on an HP OfficeJet Pro 8630 printer.

Is this possible? If so, any help doing so will be greatly appreciated.

IMHO your observation match with what is correct.

Page format is not the same as printer settings. Printer settings are different from printer to printer thus page format and printer settings must be separated.

I’m not sure, but it sounds like your answer to my question is “No, it is not possible to change the default setting in this box.” As I understand it, the LO Help (“paper trays”) says that this should be possible. If you are correct, can you tell me what is this “Page tray” setting? What is it intended to do? And how can it be set to something other than “[From printer settings]”?