Four year olds aren't known for their impulse control. :-)
What really really helps with my four year old boy is to tell him exactly what I expect of him before entering a building (like in the car on the way there). Reminding him as we are walking to the building, and quietly reminding him if he starts acting up.
I also use "fun" ways of saying it. Like "C, when we get to the store we are going to walk very slowly like a turtle, do you know how slowly a turtle walks?" Or "C, We are going to be very quite like little mice, have you ever heard a mouse"
Good luck!!
you're not alone