Bicycle Tutor

I am having problems centering the V brakes on my son's mountain bike. I know there are other threads explaining how folks fixed their specific issues. They've been a bit helpful, although I'm still having problems.
The purpose of this post/thread is this. I've seen in several places on the Internet that you use the little screws near the pivot point of the V brake to correct centering problems. But unlike instructions for dérailleurs, I don't see much information on exactly how to do this. In other words, if one brake side is moving more than another, which brake's adjustment screw do I turn? Which way, in or out? When do I use the screw on the opposite side? I was thinking if someone could explain to me the concept behind turning these screws and how it works, we all might benefit. For example, does turning the screw actually change the spring tension on that side? Or does it add drag to the lever so it doesn't move as easily, etc.
With dérailleurs, it is clear that turning the stop screws move the mechanism, it is not clear to me what these little centering screws on the V brakes do.
If this is explained in detail somewhere, just route me there please. Thank you!

These screws change the tension on the springs. I think it varies by brake whether screwing them in means more tension or less, so you may have to experiment a little.
If you just need a slight adjustment, you can probably just turn one side a little. Give it a little turn and then tap the brakes a couple times to see what changed. There's no hard and fast rule about adjusting one or both, do what you need to do to get it right. Though if one screw is all the way in and the other is all the way out, that would probably indicated the springs are off balance for some particular reason you might want to investigate.
If adjusting the screws doesn't produce clear, consistent results, try taking apart the brake arms and cleaning and relubing everything.