Can you see any diference ? ....

Code:
int arrGameBrd[8][8];
int arrSolveBrd[8][8][8];
void ChangeOneValue();

void ChangeOneValue() {
  // Declarations
  int xCoor;
  int yCoor;
  char xyValue;
  int intxyValue;
  int count;

  //BoardOut(0, 0); // I commented this to narrow down possible error location
  cout << "Enter x coordinate(1-9) for the square to be changed." << endl;
  cin >> xCoor;

  if (xCoor < 1 || xCoor > 9) {
    cout << "Invalid coordinate!" << endl;
    return;
  }

  cout << "Enter y coordinate(1-9) for the square to be changed." << endl;
  cin >> yCoor;

  if (yCoor < 1 || yCoor > 9) {
    cout << "Invalid coordinate!" << endl;
    return;

  }

  //BoardOut(xCoor, yCoor); // I commented this to narrow down possible error location
  cout << "Please enter the value for this square(1-9). Enter 0 to cancel." << endl;
  cin.sync();
  cin.get(xyValue);
  cin.sync();
  intxyValue = (xyValue - 48);

  if (intxyValue < 0 || intxyValue > 9) {
    cout << "Invalid value! Must be 1-9!" << endl;
    return;

  }
  xCoor = (xCoor - 1);
  yCoor = (yCoor - 1);
  cout << xCoor << ", " << yCoor << endl; // added this line to find the problem, will refer to is as DBline0 below
  cout << arrGameBrd[xCoor][yCoor] << ", " << arrGameBrd[1][0] << endl; // added this line to find the problem, will refer to it as DBline1 below
  arrGameBrd[xCoor][yCoor] = intxyValue; // HERE'S THE PROBLEM LINE, see output below
  cout << arrGameBrd[xCoor][yCoor] << ", " << arrGameBrd[1][0] << endl; // added this line to find the problem, will refer to it as DBline2 below
  if (intxyValue != 0) {
    for (count = 1; count < 10; count++) {
      if (count == xyValue) {

      }
      else {
        arrSolveBrd[xCoor][yCoor][(count - 1)] = 0;

      }
    }
  }

  return;
}

Please use code tags !!


Regards.