Regarding WORDSNET-16883, please check below the further analysis details:
The differences you are observing between Aspose.Words versions are related to how Aspose.Words writes the PDF File Identifier. Before 16.11 version Aspose.Words did not write File Identifier for PDF 1.5 compliance, only for PDF/A. Starting from 16.11 version Aspose.Words writes File Identifier for PDF 1.5 compliance too. File identifier is generated based on DocumentInfo. Thus when the same document is saved to PDF twice (or two documents with the same DocumentInfo), the output PDF files will have the same File Identifier. Starting from 18.5 version Aspose.Words generates unique File Identifier. Thus saving even the same document to PDF twice will produce different File Identifiers.
In Internet Explorer 11 PDF files are opened with some sort of Acrobat Reader plug-in. This plug-in seems to save the view settings of the PDF files based on the File Identifier. For the PDF files without identifier it does not save the view settings at all.
So upgrading to latest version of Aspose.Words i.e. 18.5 should help you. Please let us know if upgrading to 18.5 resolves the problem on your end?
In Internet Explorer 11 different PDF files generated by Aspose.Words from the same document will not save the view settings anymore. However opening the same PDF document twice will save the view settings anyway unlike the Aspose.Words 16.9 output without the File Identifier.
P.S. In standalone Acrobat Reader application this behavior is controlled by “Preferences->Documents->Restore last view settings when reopening documents” flag. Maybe there is some way to tune the Internet Explorer 11 plug-in either.