There should be a few xml files in your Mach3 folder, one called Mach3Mill.xml, one Mach3Turn.xml and another Mach3Plasma.xml there may be more if you have custom profiles. Not to worry anyway if you now have it running.
Not sure what you mean by returning to center but the jog screen should stay where you drag it even after a shutdown of Mach, the next time you press the tab key it should remember how you set it.
When you lived in?
Hood