whether io manipulators has to be set for every time in ostringstream?

Question

I have the following code

int main()
{
   std::ostringstream v1,v2;

   v1<<setw(5)<<setfill('x')<<5;
   v1<<6;
   std::cout<<"Version 1: "<<v1.str()<<std::endl;

   v2<<setw(5)<<setfill('x')<<5;
   v2<<setw(5)<<setfill('x')<<6;
   std::cout<<"Version 2: "<<v2.str()<<std::endl;



   return 0;
}

In version 1, i have set the manipulator first time. But the when printing 6, it was not filled with 'x'.

In version 2, i have set the manipulator both time. But the when printing 6, it was filled with 'x'.

Whether manipulator has to be set every time (or) am i missing anything here?