I ran sitemap generator and in the HTML version saw that it uses <Title> for description of HTML files and file name for description of PDFs, Videos, MP3s, etc. So I modified a few hundred files, fixed all the links, ran Dreamweaver link checker. All is OK.  But when I SCAN WEBSITE, the scan is not picking up the modified <TITLE> information or the modified file names of PDFs, etc.

Please tell me what step I am missing

Thank you, Carol

1)
Did you also recreate/upload the sitemaps after website scan?

2)
You have not told A1SG to keep titles persistent across scans?
http://www.microsystools.com/products/sitemap-generator/help/sitemapper-program-page-titles/

3)
You can configure what A1SG uses when creating HTML sitemaps:
http://www.microsystools.com/products/sitemap-generator/help/generate-website-html-sitemap/
(does not have to be titles)

4)
If problems persist, email your project + include description of URLs you believe appear incorrectly in generated HTML sitemaps:
http://www.microsystools.com/home/contact.php