so when you fill the array of *enums* you fill it with ints, or the ascii value of the characters you used.
the quick fix is to make this
Symbols gameboard[SIZE][SIZE];
into this
char gameboard[SIZE][SIZE];
there are other ways but that should let you print the thing and see what you want to see. Just remember that char arrays print until a 0 char is reached so you might want:
char gameboard[SIZE][SIZE+1];
and
for(dx = 0....... size)
gameboard[dx][size] = 0; //set the end of string on all of the rows so you can just print them with a cout statement easily.