Edit cities in the Clock widget
Question and answer... couldn't find out how to edit. Discovered that you go to the bottom of the widgets (after clicking on date and time in Big Sur) click "edit widget" - click on the 4x clocks to edit, they spin around to show list (and lines on the right to alter order) then just double click on a city, a search box comes up, type the city you need and do the same to the other 3 if required and save.