Configure Preview for Thumbnail Previews Click the Show Thumbnail button in Preview's toolbar and select the PDF thumbnails on each PDF file page. Then, click Save.... 15.6.2/17.3.14: Remove thumbnails? Open Preview by clicking the View button in the bottom-left corner of the toolbar, select Files and Preferences, then click the Preview tab. Click the PDF icon on the right side of the PDF preview and choose 'Thumbnails: Off'. Q: What is thumbnails? In a nutshell, thumbnail previews are thumbnails embedded in the PDF. Preview automatically generates thumbnails (sometimes called “thumbnails”) for each of your files. Q: Why don't I get thumbnails when I open my files? One reason is that if you want to edit the thumbnail, there's a limit to the total number of PDF files that can be opened simultaneously. The limit is 25. Another reason is because when Preview generates a thumbnail, it saves it to your Photos folder and only then saves the resulting PDF file with that particular thumbnail attached so that you can easily open the PDF file or print it with that thumbnail attached. In some cases, Preview may not automatically generate the correct thumbnail. In that case, try one of the following workarounds: 1. Click the Preview button in Preview's toolbar, then select Files and Preferences, then click the Preview tab. Click the Print button to generate the correct thumbnail. 2. Click the File option in the menu bar of Preview and then drag the thumbnails you want to use to the Preview window. 3. On a Mac with Preview, click the View menu, then click Remove and Save the Thumbnail. Q: How do I change how Preview displays thumbnails? A: Click the View button in Preview's toolbar and select Files and Preferences, then click the Preview tab. Open the PDF document by clicking that PDF document's name or by dragging the thumbnails to the Preview window. Q: The Preview toolbar in Finder is grayed out or the Preview button is grayed out Select a document in Preview. (You may have to move the document to the Preview window.) Move the document to the Finder, by right-clicking the document's title bar and selecting Move. Click or tap on the Preview button in Finder to generate the correct thumbnail.