If you've saved a document as a PDF, then it's file type will be a PDF, which you can verify by right-clicking on the file and clicking "Properties" in the context menu. From what you've said so far, it sounds like you're seeing the document's desktop (or file browser) ''icon'' displaying a Firefox icon. All that really means is that the PDF file is associated with Firefox and will consequently open in Firefox by default (ie: when double-clicked) rather than Adobe. If that's the case, then it is in fact not an HTML document. You just need to change the default file association for PDF documents away from Firefox, back to Adobe, which will change the document's desktop icon back to the more familiar Adobe icon. These links should help guide you in getting this done: https://www.online-tech-tips.com/windows-10/how-to-change-file-associations-in-windows-10/ https://support.microsoft.com/en-us/windows/change-default-programs-in-windows-10-e5d82cad-17d1-c53b-3505-f10a32e1894d

Open the computer's file browser. Locate that type of file and right-click on it. Select '''Properties.''' Under '''General,''' look for '''Opens With''' and press '''Change.'''