Implement Merge Sort for two dimensional Array and more than one column

Recently I found a competitive programming question that need to add merge sort for 2d array arr[i][j].

row and column count i & j get from user input.

It isn't a good solution if you have input lower row count(assume I && J < 100). But it getting a big integer. Insertion sort is not that good. So I hope to add merge sort instead of that. Specialty is that two of columns needs to be sorted out also

A 2D array which has two columns. How can I implement it more efficiently? It is costly to swap two values when the rows are getting higher and higher. Is there a way to implement it easily.

Here is my insertion sort implementation.

insertionSortA(Cq,globalC);
    for(int i =0;i<globalC-1;i++){
        for(int j =0;j<globalC-i-1;j++){
            if(Cq[j][1]>Cq[j+1][1]){
// swapping 
                my_temp = Cq[j][1];
                Cq[j][1] = Cq[j+1][1];
                Cq[j+1][1] = my_temp;
                my_temp2 = Cq[j][0];
                Cq[j][0] = Cq[j+1][0];
                Cq[j+1][0] = my_temp2;
            }
        }
    }

This is only a simple code to demonstrate the idea

If you have anything special ideas. Please put an answer. Thanks in advance.