How do I change the configuration.h

Hi, can anyone tell me what I need to change in Marlin configuration.h so I can have a hanging z axis please.
I go in to config.h and go down to invert z dir, type true.
but when i ask to verify i keep getting an error message : usingtypedef-name ‘fpos_t’ after ‘struct’
Hi, I changed the Arduino version back to 1.0.5 and have managed to invert the axis so the hanging z axis now works the way I want it too,

Ted