When i create a "content type" i disabled showing "author name" and "posting date". Then i created nearly 100 nodes from that type of content. Now i want to show posting date in node content.

When i edit the node and enable showing post date. Everything OK. Post date is shown. But when i edit content type and enable post date, i can't see posting date in content page.

It is hard to edit all nodes to show post date. Is there a better way? Thank you very much.