By default, the main movie title will be selected by DVDFab, if you want to convert other titles, use the "Choose Other Titles" option to pick the one you need. Click on the movie title to select it, and then you can change the Title name, select chapter, choose audio tracks and select the subtitle streams you prefer for the process.
You can use the button to preview the content of the selected title, and use to remove the title you don't want to convert/rip from the list.
In the drop-down list of Audio and Subtitle, if you put the tiny white triangle in front of one of the track/stream, the marked one will be the default one for playback.