If the thumbnail viewer allows customization, you can configure how thumbnails are displayed. The thumbnail viewer lets you change the thumbnail size, the preview size (if applicable), and the number of columns displayed.
Note:
If the Thumbnail Options button is unavailable in the thumbnail viewer, then customization has been disabled. If you are having trouble previewing documents and the Thumbnail Options button is unavailable, ask your system administrator to adjust the viewer's display settings.
To configure the thumbnail viewer options: