Castled position

I know that when I move any of the three pawns in front of my castled King I compromise King safety. In comparing my moves with the computer I find that it wants me to move these pawns earlier and way more often than I do.

I don't necessarily know why the computer wants to make these rules. Does anyone else have the same problem? Can anyone give me a general principle to guide me in this decision?

A principle for the three pawns in front of the castled king is that they should remain in their original positions.  But, as you know there are exceptions to every pinciple or rule.  Just as in mathematics there are no absolutes, and the exception proves the rule.  

There is a general principle, but it applies to the entire board, not just the pawns in front of the castled king, over the entire game.  This principle encompasses the exceptions to principle that the three pawns in fron of the castled king should remain in their original positions.

The principle is:

Winning chess is the strategically and tactically correct advance of the pawn mass.

If you would like to know the details of how this principle is applied with every move in a chess game you need to study endgames.  You can begin with endgame material here on chess.com.  But if you get serious about the game you will need Dolmatov's endgame data base and Yuri Averbach's endgame series.

For a more general treatise on pawns you will need, "Pawn Power In Chess ", by Hans Kmoch.  

I generally prefer my pawns "flat" as well.  Pawns are the only entity in the game that can't take their moves back.  Once you move it, the old square is gone forever.  Proceed with caution!

Some reasons to move a pawn in front of the king.  You may fiancetto your bishop, where the knight pawn is moved out one square.  A perfectly acceptable defense.  You might move your rook pawn out one square to harass minor pieces on the 4th rank - this can backfire if your opponent is ready to sacrifce his bishop for your rook and knight pawn, leaving you exposed.  If you are both castled kingside, it is quite common for white to play f4, attacking the center.  (Or black to play f5.)  Those pawns are guarded by the castled rook and can contribute greatly to an attack, as long as your king is safe.

I take great care when moving those pawns, and I usually only do it when I feel confident my opponent cannot effectively attack me.  I have been known to use ALL of my defending kingside pawns to attack a weak enemy position if my opponent has put all of his resources on the queenside.  That's a roll of the dice that I am going to get a checkmate - if the plan fails, it could be a disaster!

I don't know if any of that helped, but always be cautious and use your best judgement.