I’ve analyzed your documentation for newer SDK dll(GroupDocs Viewer v 3.0.), looks like your are doing conversion as docx file to html or image.
So as per your previous version GroupDocs Viewer v2.18, you were having some user control for previewing the document does the latest version have some user control for previewing or something other.
And please let me know, how to extract text data from docx file using your latest SDK.
Please let me know as earliest as possible.
Looking forward to hear your response.