Well, if you run qBittorrent as root, the user changes and thus qBittorrent folders too:
/root/.qbittorrent
/root/.config/qBittorrent
/root/qBT_dir
Then, of course, the torrents of your former user will not be downloaded by root. Torrents cannot be shared among users. I think that maybe you should have a look at the permissions in ~/.qbittorrent/BT_backup
Well, if you run qBittorrent as root, the user changes and thus qBittorrent folders too: config/ qBittorrent
/root/.qbittorrent
/root/.
/root/qBT_dir
Then, of course, the torrents of your former user will not be downloaded by root. Torrents cannot be shared among users. I think that maybe you should have a look at the permissions in ~/.qbittorrent/ BT_backup