Pick all means you are considering all instances, it is useful if you picked some instances but you want to have all picked once again (never happened to me to have to use it), pick all is automatic at the root of events, it does not imply that you will repeat for all instances treating each of them individually (actions will execute for all of them, but expressions will only use one reference instance).
For each means you will apply what is next to all currently picked instances of that object individually, for each is implied in a lot of objects conditions (not all of them, on timer is an exemple that does not imply it), which means that expressions will be evaluated separately for each object.
Right under your picking, I guess a for each is needed.