Added LG monitor and cannot get display icon to show MAC 10.3.6 cannot get the display icon to show up on the menu bar of my macbook pro AND the attached monitor.

(older) LG 24M47H-P
Display preferences show LG Full HD 

✔️ Show mirroring options in menu bar when available.

What am I missing, this worked with my old Mac running Snow Leopard.
To show the Apple Menu Bar on both displays, (and thus see the Monitors menu item,) Check "Displays have separate spaces" in System Preferences > Mission Control.