This isn't on the preferences screen as such.
The way it works has changed. TV Show folders can now be added as a single directory or as a root directory :-
No scraping is done until save and exit is selected, then -
Each show without a tvshow.nfo file does a quick scrape getting only the basic information from a single page, this takes a second or so for each show, depending on TVDB (Not the fastest site). Some user intervention is required to make sure that the correct show is scraped.
Once all the shows have this then a full unattended scrape is offered, that is the opions you are seeing.
Once you have chose your settings then just click go. If you have added 20 shows then set it going and go and get a cuppa, much the same as episode and movie scraping etc. The ammount downloaded is really quite small (between 1 & 5 MB depending on the ammount of fanarts and TV Series thumbs that are downloaded.) TVDB can be very slow and even this ammount can take some time.