Jejeje great that you fixed it because I have to admit that I'm completely lost with this post, my head is going like Meeeeh!! in the good way of course
On start of layout: Is a trigger that is (Triggered or Fires) when the layout begins. Meaning that it Only happens once and it happens always at the start of the game.
What are Triggers??
This indicates that the event is triggered. Rather than running once per tick, this event simply runs (or "fires") upon something actually happening. In this case, the event runs when the layout starts. It is never checked any other time. Since triggers run upon an event happening, they aren't checked in top-to-bottom order like other events. This means the ordering of triggers relative to other events is not important (except relative to other triggers of the same type, since triggers still fire top-to-bottom).
Normally you recognize the triggers by the green arrow and the most of them if not all start by (On)
Example: On collision, On Jump, On Created, On Destroyed etc....... those are all triggers that run once every time the condition is met.
Every Thick: is A condition which is always true Any Action you add here it will be updated 1 per thick which is = 60 times a second in most of the Pc, Meaning that is for actions that you need to update continuously none stop,
You can test it out by yourself really quick all of this, you see this capx we wanna make the car1 follow the car2 continuously and we make this by setting the angle from car1 to car2, but once you run it the first time you will notice that it will not follow the car2 because the set angle action only triggers once and it will happen only once this will only work if the car2 will be not moving, but the car2 its constantly moving so the set angle it will have to keep updating every thick to keep track of the car2 angle, so this will only work if you use the (Every thick)
So now move the Action from the (Start Of Layout) to the (Every Thick) and you will see that now is working great because the angles are keeping updating every thick, I hope it makes sense for you if not you can ask.
You should check the tutorials (system-conditions) and (How Events Work) to have a better view.