Maybe there's a clear explanation for this already, but I am wondering why in-game it says that I'm green belt, but on the website, my account says I'm orange belt. Anyone?

I'm guessing you're talking about in your playercard? Well, how long ago did you acquire green belt?
The forum isn't up to date all the time, it should update within the next day and you should also receive your achievement.

you must wait until got message from toribot
and than you will get that achivment(means get that belt picture in forums)
just be patient it will come automaticly

Usercards update every 24 hours, while in-game qi earnings update after every match.

Just press the update button beside it. That works.

the player card updates 24 hours after you commit an acheivement

Thanks, guys. I just noticed I got the achievement.