On single pole switches I install with 2 screws to the right side, this makes it up for on.
On 3 ways I like to maybe turn one "Upside Down" if needed so when all switches are switched off in multiple locations and 3 and 4 ways, everything is off. In the photo , it almost looks like the switchleg(white wire) made contact with the ground on single pole switch, If they touch when switch is installed and shock occurs when light is on(3 way light). Then that may be problem?