Hi Bob, do you mean for files you download in Firefox? Try using the recent downloads list that appears when you click the Downloads button on the toolbar. Right-click the download on the list and choose "Always Open Similar Files" to have Firefox create a new entry in the Applications list. If you need to make further changes, check out the steps in this article: [[Manage file types and download actions in Firefox]]. There may be cases where "Always Open Similar Files" is not available either because the file extension is executable or because the server didn't spell out what kind of content it was. In that case, some further trickery might be required... Any luck so far? If you meant in Windows, for File Explorer purposes, search in the system search box for ''default apps'' and see whether you can set it there.