Select the city you are interested in, then in the City Window (see manual), click the add ('+') or edit ('o') button below the zoom slider and it will set the city to show up at your current zoom level. Zoom to your elevation that you want it to show at and click the save ('x') button directly below the zoom slider to save it. To remove a city's icon select the city and click the delete ('-') button. Please note that weather icons will not show up with the weather dataset turned off.