I was unable to find a "Global Configuration" menu as well, Richard. So I took a quick look (on Linux) at the "tws" shell script that starts my TWS.
At the end of the scrip, when it assembles the final Java VM command line, it adds the definition "-DjtsConfigDir=\${installer:jtsConfigDir}" that seems to hard-wire the settings folder. I added a "/lalala" for fun and that shows up right in the greyed out folder dialog on the login screen.
So I guess you'd need to fiddle with the startup script to modify that folder.
´³¨¹°ù²µ±ð²Ô
PS. While looking into this I stumbled over the fact that tws.xml and ibg.xml are now encrypted as well. At least in 10.17
