Preview in Browser preferences display the currently defined primary and secondary browser. To open Preview in Browser preferences, choose Edit > Preferences, or File > Preview in Browser > Edit Browser List.
Edit changes settings for the selected browser.
Remove deletes the selected browser from the list.
Primary Browser and Secondary Browser specify whether the selected browser is the primary or secondary browser. F12 and F11 open the primary browser and secondary browsers respectively.
Preview online (Windows only) supplies the current page for previewing by a local server as a URL beginning with http://localhost/. With this option off, Dreamweaver opens the document in a browser with a file path beginning with file://. In some cases links specified as site-root relative paths do not work correctly when opened in a browser with a file:// path.