Changing mentality and instructions in between the game

I always use standard mentality and no instructions for the defensive line.

Now let's say my opponent gets ahead of me @ 60th minute or so.

Now what do I do?

If I change the mentality to overload and instruction to much higher defensive line, they will less accomplished or fluid. Hence reducing chances of playing well.

But if I don't do that, then they won't be much aggressive hence not highly likely to score in remaining time.

So what do I do?

I always use 4 4 2 dm.