Why is subtraction not associative?

commutative means the numbers can be put in a different order and equal the same thing such as 3+4=7 and 4+3=7. the subtraction problem 7-3=4 is not commutative because if u switch the 3 and 7 the equation is 3-7=-4. the numbers are in a different order but you dont get the same answer so its not commutative