chess score/points

The more games you play within a time control, the smaller the changes in your rating. That's a function of the Glicko RD rating system that chess.com implements. The ratings deviation (RD) goes down the more games you play which means your rating becomes more accurate.

Thanks

today i won a guy with score 1800, and my score is 1576, and i win no scores, why?

Your opponent hadn't played a game  in that time control before and his preset rating was 1800, probably why.

Your game against dade58 was unrated.

is this a system bug or is this game invalid? but it is just a normal game, no cheating, no breaking the rule.

There is nothing wrong here.

Games are either rated or unrated. Either you accepted or created an unrated challenge.