using System;
using static System.Console;
using System.Linq;
using System.Collections.Generic;

class Program
{
    static int NN => int.Parse(ReadLine());
    static long[] NList => ReadLine().Split().Select(long.Parse).ToArray();
    public static void Main()
    {
        Solve();
    }
    static void Solve()
    {
        var t = NN;
        var ans = new string[t];
        for (var u = 0; u < t; ++u)
        {
            var n = NN;
            var s = ReadLine();
            if (n == 1) ans[u] = "B";
            else if (n == 2) ans[u] = "BB";
            else
            {
                var c = s.ToCharArray();
                if (s[0..3] == "ABA")
                {
                    c[0] = 'B';
                    c[1] = 'B';
                    c[2] = 'A';
                    var begins = false;
                    var ends = false;
                    for (var i = 3; i < n; ++i)
                    {
                        if (!begins)
                        {
                            if (c[i] == 'B')
                            {
                                begins = true;
                                --c[i];
                            }
                        }
                        else if (!ends)
                        {
                            if (c[i] == 'A') ends = true;
                            else --c[i];
                        }
                    }
                    ans[u] = string.Concat(c);
                }
                else if (s[0..3] == "BBB")
                {
                    ans[u] = s;
                }
                else
                {
                    if (c[2] == 'B') for (var i = 3; i < n; ++i)
                    {
                        if (c[i] == 'B') c[i] = 'A';
                        else break;
                    }
                    c[0] = 'B';
                    c[1] = 'B';
                    c[2] = 'A';
                    ans[u] = string.Concat(c);
                }
            }
        }
        WriteLine(string.Join("\n", ans));
    }
}