在当前数组的 $a_x$ 与 $a_{x+1}$ 之间插入 $y$。

读题啊！你看看你中间往后交换的数是怎么换的，是要从插入位置依次往后移动。

while (temp>0)
	{
		int old, nwe;
		
		cin >> old >> nwe;
		
		n++;
		int na = x[old+1];
		for (int j=old; j<n; j++ )
		{
			int nb = x[j+1];
			x[j+1]=na;
			na = nb;
			
			
		}
		
		x[n+1] = na;
		x[old+1]=nwe;
		
		temp--;
	}

正常就从后往前顺次移动就好了，简单的赋值运算 a[i + 1] = a[i];，你交换会影响后面的数值。

#include <bits/stdc++.h>
using namespace std;
int n, m, x, y;
int a[21234];
int main()
{
    cin >> n;
    for (int i = 1; i <= n; i++)
        cin >> a[i];
    cin >> m;
    for (int t = 1; t <= m; t++)
    {
        cin >> x >> y;
        for (int i = n; i >= x + 1; i--)
            a[i + 1] = a[i];
        a[x + 1] = y;
        n++;
    }
    for (int i = 1; i <= n; i++)
        cout << a[i] << " ";
    return 0;
}