If you have multiple/individual sheets within your Excel workbook, when you try to create a PDF and choose to print the Entire Workbook, you will receive a PDF file containing only part of the Excel document or each sheet will be saved as a different PDF file.
This happens because multiple sheets in your workbook have different dpi settings for printing. Excel assumes that all your individual sheets have different page setups, so it sends them as multiple print-jobs.
In order to have all the individual sheets printed within a single
PDF file (not multiple PDFs) you need to set the same page setup options
for all of them (page setup in Excel modifies the print size of the
resulting file, so for example if you set the page layout to landscape
in Excel, the printed page will be landscape but your original Excel
file will still maintain the same view).
To set the same Page Setup options for all individual Excel sheets:
Open the Excel workbook.
Select a sheet or multiple sheets you want to set the DPI for.
In Microsoft Excel 2007/2010/2013/2016, go to Page Layout and click on the expand button for Page Setup dialog as the attached screenshot(for Microsoft Excel 2003 or earlier go to File->Page Setup) .
In the Print quality section enter the DPI value that you want to have for your document and press OK.
Go to File ->Print, select Foxit PDF printer from the Printer name list, and select Print Entire Worksheet under Settings and click on Print to create the PDF file.