Let's briefly look at the most commonly-used viewing options.
Display the Viewer tab of the PDF export dialog. In this tab you can choose between a predefined action or, at the bottom of the window, define your own custom actions if you've added some with your own JavaScript functions.
Let's begin with the default options, which are quite easy to understand. Click on the Double Page Right in the Document Layout category.
In Visual Appearance, choose the Display Bookmarks tab to help the user navigate in your document.
Finally, if you want to define some advanced display option, you will have to do so with your own JavaScript actions. If you want to choose your script from the drop-down list of the Viewer tab, you'll need to inform Scribus first about the JavaScript functions that you want to create. By going to Edit | JavaScripts, you will get a new window in which you can Add some scripts. Click on the button and give it a name; here...