"Display Command Line" should be an option in the monitor settings, not the PSD.
Using the software on my laptop (one monitor), there is no option for "Display Command Line" - I assume this is because they don't want us to be able to have no command lines at all.
Using the Gio at work, each PSD has a "display command line" option. This toggles the command line visibility on the monitor with the highlighted tab (except for monitor 1, whose command line can't be hidden. This is very misleading.
If I want to hide the command line on monitor 3, I click on the PSD tab on monitor 2 if it isn't at the top, then click on the tab on monitor 3, then click the gear on Monitor 2, then click the empty "Display Command Line" check box in order to put a check in it so I can deselect it and hide the command line on monitor 3.
Also, clicking on a tab brings back the command line on that monitor.