The best method to get both accurate metadata and the PDF is to use the Zotero Web Connector on the article's web page (without clicking to open/download the PDF yourself). If any of the metadata shown in the resulting parent item's fields is incomplete or inaccurate (which is relatively rare), you can update it by typing it in manually. https://www.zotero.org/support/adding_items_to_zotero
Thank you for sharing information.
I could understand that it's impossible to edit PDF infos directly.
https://www.zotero.org/support/adding_items_to_zotero
Thank you for let me know a good way to record PDF files!