/**
	author:  shobonvip
	created: 2025.12.26 15:22:59
**/

#include<bits/stdc++.h>
using namespace std;

//* ATCODER
#include<atcoder/all>
using namespace atcoder;
typedef modint998244353 mint;
//*/

/* BOOST MULTIPRECISION
#include<boost/multiprecision/cpp_int.hpp>
using namespace boost::multiprecision;
//*/

typedef long long ll;

#define rep(i, s, n) for (int i = (int)(s); i < (int)(n); i++)
#define rrep(i, s, n) for (int i = (int)(n)-1; i >= (int)(s); i--)
#define all(v) v.begin(), v.end()

template <typename T> bool chmin(T &a, const T &b) {
	if (a <= b) return false;
	a = b;
	return true;
}

template <typename T> bool chmax(T &a, const T &b) {
	if (a >= b) return false;
	a = b;
	return true;
}

template <typename T> T max(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmax(ret, a[i]);
	return ret;
}

template <typename T> T min(vector<T> &a){
	assert(!a.empty());
	T ret = a[0];
	for (int i=0; i<(int)a.size(); i++) chmin(ret, a[i]);
	return ret;
}

template <typename T> T sum(vector<T> &a){
	T ret = 0;
	for (int i=0; i<(int)a.size(); i++) ret += a[i];
	return ret;
}

string alice_choice(string s) {
	int n = (int)s.size();
	if (n <= 2) return s;
	if (s[0] == 'A') {
		if (s[1] == 'A' && s[2] == 'A') {
			s[1] = 'B';
			return s;
		} else {
			int mode = 0;
			rep(i,0,n) {
				if (mode == 0 && s[i] == 'B') {
					mode = 1;
				} else if (mode == 1 && s[i] == 'B') {
					mode = 2;
					s[i] = 'A';
				} else if (mode == 2 && s[i] == 'B') {
					s[i] = 'A';
				} else if (mode == 2 && s[i] == 'A') {
					mode = 3;
				}
			}
			return s;
		}
	} else {
		if (s[1] == 'A') {
			return 'B' + alice_choice(s.substr(1, n-1));
		} else {
			s[0] = 'A';
			return s;
		}
	}
}

string bob_choice(string s) {
	int n = (int)s.size();
	int mode = 0;
	rep(i,0,n) {
		if (mode <= 1 && s[i] == 'A') {
			mode = 1;
			s[i] = 'B';
		}else if (mode == 1 && s[i] == 'B') {
			mode = 2;
		}	
	}
	return s;
}

void solve() {
	int n; cin >> n;
	string s; cin >> s;
	string t = alice_choice(s);
	string ans = bob_choice(t);
	cout << ans << '\n';
}

int main(){
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	int t; cin >> t;
	while(t--) solve();
}