Retaining the default size in Sketchup

Hi
Trying to use Sketchup and Sketchucam to get the Gcode for my Ox, but I'm having trouble keeping the default size. When I transfer the drawing from Inkscape its 609.6mm wide and 914.4mm long (2' X 3').

But after getting it into Sketchup its 4ft wide and 9ft long. I've tried changing the default dimensions but every time I use Sketchup the sizes change back to feet again.

Its Sketchup 2015.

Any suggestions.

Thanks.