Take the round knurled nuts off, and replace them with hex equivalents (sometimes hard to find for oddball sized or metric sized switches)
Or, if you have a hex type "backup nut" behind the panel to adjust how deep the threaded part of the switch sticks thru the panel, you can always reverse them and put the round nuts behind the panel and the hex ones on the front side so you can tighten them with a box-end wrench that won't slip and scratch the panel. I also always use thin washers under the hex nuts of toggle switches and breakers to help prevent scratching the panel.