Crucial Step: Go into Options > Preferences > Directories . Ensure that your "Download" folder is set to a relative path on your USB drive so that your files move with the software. Security and Best Practices
Often, installing software on public or work computers requires admin passwords. Portable apps typically bypass this requirement since they don't modify system files. bittorrent portable
Despite its "lightweight" reputation, BitTorrent Portable usually retains the full feature set of the main client: Crucial Step: Go into Options > Preferences > Directories