In your old Opera 12.16 save your old bookmarks as an HTML file on your hard drive. Settings>Import export>export bookmarks as HTML
Save them with a name such as MYBOOKMARKS
Now open them in old opera PAGE>OPEN>MYBOOKMARKS
Now when all the Bookmarks appear in the link above that displays the link mouse over the link and RIGHT CLICK MOUSE and hit COPY
CLOSE your old Opera 12.16 Browser.
OPEN your new Opera 20.00 Browser. Clear the existing link and Right Click Paste and Go!
Insert the MYBOOKMARKS into your new Opera 20.00 Browser and save.
NOW all your old bookmarks are available in your in Opera 20.00