So i just got BBS Final Mix and i started playing it and i realized something...in Japan both BBS and BBSFM use the circle button for attacking and the x button to jump. So i was just wondering why that is?

I'm not exactly sure why, but I'm aware gameplay for KH in Japan has always been O for attack and X for jump.

All Kingdom Hearts games in Japan use different controls to that of the English version.

I got used to that after playing KH2FM alot so yeah they always switch between O and X 

Most Japanese Playstation games use the O button as confirmation and X as cancelling, or otherwise swap them out completely like with Kingdom Hearts.

I didnt know this, but I do prefer X for jump in games, although the way it is in KH works for me.

Most Japanese Playstation games use the O button as confirmation and X as cancelling, or otherwise swap them out completely like with Kingdom Hearts.

 

Basically this.  Usually O is good and X is bad.  So in Japan if you're homework is handed back and has a lot of circles on it, it means you did good on those answers.

All Kingdom Hearts games from Japan are like that.