Even though I have tried to customize my Time & Dates settings (both via Trinity Control Center => Regional & Accesibility => Country/Region & Language => Time & Dates, and Clock => Date & Time Format), my settings do not appear in the Clock applet's panel gadget, nor in the Calendar that pops up when the Clock gadget is clicked. I have attached a screen shot of the pertinent screen areas.
Leslie -- Platform: Linux Distribution: openSUSE Leap 15.6 - x86_64 Desktop Environment: Trinity Qt: 3.5.0 TDE: R14.1.3 tde-config: 1.0