Can't work out how to change Transmission download location

I've got a separate volume set up that I'd like to use to store torrents in. Currently I'm able to download to my main volume and the location is set to /etc/zyxel/storage/sysvol/oohNASty/Seedbox where "oohNASty" is the name of the share and "Seedbox" is a folder on that share. If I change it to "/etc/zyxel/storage/sysvol/Seedbox" where Seedbox is the name of the new volume then the data disappears but it doesn't appear on the new or the old volume so I have no idea where it's going. I'm sure I've set this up in the past to download to a different location but I can't remember how I did it! how do I tell torrents to go to the new volume?