Your explanation, now, is perfectly understandable (I just wanted more details, that’s all)… so don’t worry about your English. 
When BitComet connects to the Tracker, it, in turn, sends out a list of all of the peers that are connected in the swarm, at that moment. The tracker usually ‘updates’ that list, after a specific amount of time (20 minutes is the average), and will, once again, send the ‘refreshed’ copy to everyone in the swarm.
Apart from the actual interchange of pieces between the peers (the contents of the torrent file), there is also an additional traffic, which is known as “overhead”. This overhead is actually, pretty much continuous as it is the interchange of information (and negotiations) that occur between the peers’ clients (“I have piece ABC. Do you want to trade with me?”… “Yeah, sure.”), the trackers, etc.. It is not usually a large amount of traffic, but it is continuous.
When you stop your torrent, your client has to send the tracker a message (“Hey! I’ve stopped, now. I’m leaving the swarm.”) indicating your intentions. In the meantime, the rest of the peers in the swarm don’t know that you’ve stopped your torrent and that you’re leaving the swarm yet, so they keep trying to contact you. They won’t know that you’ve stopped and left, until the tracker sends out another refreshed/updated list to the swarm.
Also, depending on the version of BitComet that you’re using (you did not specify), you might have LT Seeding enabled (check in your Settings/Options). This means that, even though you are not downloading/uploading actively (as reflected in your task window), you actually are uploading, in the background (this feature is supposed to only use your unused (‘extra’/sobrante… surplus, if you will) upload bandwith).
That it probably the reason that you are seeing a larger upload amount in your top bar (an approximate global/total amount), than in your task window (actual per task amount).
Regards,
cassie 