Just learned something new... With "Automatic sync" off, if you select a file from the host the file is downloaded to your device and will remain so long as the file on the host is not changed. If you change the host file, the file on the mobile device is removed from BTS's listing (in the app itself) but the old file remains on the mobile device. If you change the file on the mobile device, the host is updated and the file on the mobile device remains in the listing of the BTS app. Do wish these things were documented.