Hi, do you mean that Firefox is going to "do this every time" for a particular kind of file? You can review and modify those actions on the Options page. This article has more info: [[Change what Firefox does when you click on or download a file]]. If you don't like the current action, "Always ask" is usually a safe choice. For PDFs, though, if you want to view them in a tab in Firefox, "Open in Firefox" works best. See: [[View PDF files in Firefox or choose another viewer]]. Success?