After searching the web, I found that there are 2 type of bookmark in pdf.
first is normal bookmark, with "Set Destination" option when you right-click on the bookmark.
You create this by Ctrl+B.
second is tagged bookmark, without the "Set Destination" option.
You create this by merging multiple pdfs together.
Now the question is, is there a way to convert all tagged bookmark to normal bookmark??
I have tried to delete all tags after merging, but the bookmark still does not show the "Set Destination" option.