I would like to download big file (over 5 GB) from MyAirBridge.com as free user. This service requires to click on link, then it "prepares download" for several hours but ability to save it on local disk is displayed as standard Firefox downloader window after the file is stored on temporary folder. Because of file size I got message that my temporary folder is to small (out of space) but... after downloading almost all file. I suppose it is downloaded to /tmp.
How can I change default folder of temporary files (not cache!) in about:config or other config files of my Firefox installation?
I'm using Kubuntu 17.10, Firefox 59.