You can turn off 'Browsing' in tools/Options,go to 'sharing' remove all files/folders with the 'remove' button,untick share finished downloads box. Go to '' Uploads'' option,reduce bandwidth to zero, make sure ' allow partial sharing' box is unticked (often a reason for sharing things you may not want to) Go to 'Slots' and set to zero both uploads per person and max upload slots, and I bet NO one can upload anything from you ! if any of these settings are not correct,it may result in some of what you are complaining about. some are so paranoid they will not share,it's a personal choice,although it goes against everything that the internet and freedom stands for. get some education around this, and decide what you want to do,really there is so much information and help on these forums if you try. If you worry about who is sniffing around in your computer,get yourself protection use a packet sniffer to track in and out movements etc....
balance in all things said the tightrope walker !
Good luck
N2