Arduino/CoinSlot/LCD - Variable Display. Need Help.

With this code i can't seem to get what i want to display.
x = number of Type 1 Coin
y = number of Type 2 Coin
z = number of Type 3 Coin
a = monetary total of the coins inserted

So, why not use names that make sense?

volatile int x = 0;
volatile int y = 0;
volatile int z = 0;

Why are these volatile?

  CoinChange = 1;

Why is this not declared?

What happens is that i have setup 4 variables that will be displayed in the LCD. I was hoping that with the 1 second delay it would have given the interrupt function the time it needs to count up the "coins" variable before entering the Loop function. But as a result it either does count right or only counts up the "x" variable even when the i have use Type 2 or 3 coins.

Where are your debug statements? What value does coins have, on each pass through loop?