Once you are in Script column, and all clips are selected, press T to clear any existing mark in/outs, then press Q to take you to the start of each clip,then use the 2 and 4 keys to set your new in/out points.
After this send all clips to the timeline, and set a in point at the first edit and an out point at the last edit – then go to quick transitions, select your required transition, check the box that says “Apply to all…” and then Add.