Roguelike Tutorial Expansion of Layout

Hey there, I have finished the Roguelike Tutorial on this site and I have learned a lot. Now I am trying to figure out how to expand on this game and learn even more. The first thing I wanted to do was expand the layout width and height.

My obvious first thought was to change the variables that control how many rows and columns there are.

 public int columns = 8;   //Number of columns in our game board.
 public int rows = 8;   //Number of rows in our game board.

If you take a look at the original code, the writer even commented what these two variables do. Unfortunately, changing these values has no effect. I looked throughout the rest of the code and I just can't seem to find any other way to control the board layout.

This is the last piece of code that may be helpful in answering this question.

     void BoardSetup ()
     {
     //Instantiate Board and set boardHolder to its transform.
     boardHolder = new GameObject ("Board").transform;
                 
     //Loop along x axis, starting from -1 (to fill corner) with floor or outerwall edge tiles.
     for(int x = -1; x < columns + 1; x++)
     {
     //Loop along y axis, starting from -1 to place floor or outerwall tiles.
     for(int y = -1; y < rows + 1; y++)
     {  //Choose a random tile from our array of floor tile prefabs and prepare to instantiate it.
     GameObject toInstantiate = floorTiles[Random.Range (0,floorTiles.Length)];  //Check if we current position is at board edge, if so choose a random outer wall prefab from our array of outer wall tiles.
     if(x == -1 || x == columns || y == -1 || y == rows)
     toInstantiate = outerWallTiles [Random.Range (0, outerWallTiles.Length)];  //Instantiate the GameObject instance using the prefab chosen for toInstantiate at the Vector3 corresponding to current grid position in loop, cast it to GameObject.
 GameObject instance = Instantiate (toInstantiate, new Vector3 (x, y, 0f), Quaternion.identity) as GameObject;
                         
     //Set the parent of our newly instantiated object instance to boardHolder, this is just organizational to avoid cluttering hierarchy.
    instance.transform.SetParent (boardHolder);
       }
      }
     }

By the way, tags are pointless if you can't create your own. How are tutorial, rogue, layout, and board not accepted tags?