
You have to download the file type once, then right after that Click the arrow next to that file and choose "always open files of this type". Syntaxtic extension; btw, for Firefox load the InlineDisposition add-on You will have to do it just once for various files such PDF, Excel , Excel Word, ect. Mozilla Firefox: Firefox includes a built-in PDF viewer that allows you to view almost all PDF files found on the web without a plugin. The built. PDF or PowerPoint on the web, it generally defaults to downloading it as a file. want the PDF to open in Adobe Reader instead of within the Firefox browser.