Click on the Preferences menu under the Bits on Wheels drop-down menu:

>Under Preferences, click on the "Torrent Defaults" button. Under the "Upload to Max" box, limit this to 2 peers. This is the minimum for uploading, as anything below two will result in an error message that states a number below 2 peers "Fell short of minimum." Next, click the Manual selector and limit the upload rate to 0 kb/s in the box next to the "Manual" selector:

This is the Bits on Wheels application homepage. Given the configuration above, you may see files uploading.
Cancel these as soon as possible from this application homepage by selecting the upload and then clicking the
"Remove" button near the top of the application window: