Alternately, if you haven’t added your clips to the timeline there is an easier way to add default effect to all your clips in one go. Select all the clips in your project window, under PROJECT menu select AUTOMATE TO SEQUENCE, give clip overlay frames as needed and click OK. All selected footage will be laid out on the timeline forward of your playhead position with transitions at each cut. But if you already have clips cut on the timeline you have to do one by one (Page Down, Ctrl-D).