import java.io.*;
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int t = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        while (t-- > 0) {
            int n = sc.nextInt();
            char[] values = sc.next().toCharArray();
            ArrayDeque<Character> stack = new ArrayDeque<>();
            for (int i = n - 1; i >= 0; i--) {
                if (values[i] == 'A' && stack.size() > 0 && stack.peek() == 'B') {
                    stack.pop();
                    if (stack.size() == 0 || stack.peek() == 'A') {
                        stack.push('B');
                        stack.push('A');
                    }
                } else {
                    stack.push(values[i]);
                }
            }
            while (stack.size() > 0) {
                sb.append(stack.pop());
            }
            sb.append("\n");
        }
        System.out.print(sb);
    }
}

class Scanner {
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer st = new StringTokenizer("");
    
    public Scanner() throws Exception {
        
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(next());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(next());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(next());
    }
    
    public String next() throws Exception {
        while (!st.hasMoreTokens()) {
            st = new StringTokenizer(br.readLine());
        }
        return st.nextToken();
    }
}