Just in case you were looking for a way to edit the WebUI address without opening the WebUI (because you can’t, because you only have ssh access to the server and the default address is localhost):
The config file in ~/.local/share/qBittorrent/qBittorrent.conf takes
[Preferences]
WebUI/Address=[address]


You could also install NixOS on all your headless servers and set it declaratively: https://search.nixos.org/options?channel=26.05&query=services.qbittorrent.serverConfig&type=options#show=option%253Aservices.qbittorrent.serverConfig
For instance: