Hi, Wawatobi
The XML file's are located in Your Mach3 folder, Mach3Mill.xml, copy and past it in your My Doc's folder, some where you can remember on your computer, just for safe keeping as it has all your setup/startup data.
It's the Session Profile you use at startup can be Plasma.xml, Mach3Turn.xml, Lathe.xml, or one you created with Mach.
Hope this helps, Chip