1.) When a PDF is displaying incorrectly (as in the first image below), click on the settings button in the upper right corner of the browser and select "Options."
2.) Now, click on the "Applications" tab and scroll down until you see "Portable Document Format" in the left column. In the right column, click on the drop-down menu and select "Use Adobe Acrobat (in Firefox)." Select OK.
*Note: If you'd prefer to open the document in Adobe Reader -- rather than the web browser -- you may select that option, too.