Expanded ISOs 12,800 and 25,600 are only available in JPG mode.
If you're using Fuji X lenses then you'll notice they have an aperture setting, 'A'. Also, notice the shutter speed dial has an 'A'.
The 'A' on the aperture ring and shutter speed dial means 'Automatic'.
Lens set to A, shutter speed dial set to A gives you Auto.
Lens set to A, shutter speed dial NOT set to A gives you Tv.
Lens NOT set to A, shutter speed dial set to A gives you Av.
Lens NOT set to A, shutter speed dial NOT set to A gives you Manual.
You might find it useful to have a look at the user manual -
http://www.fujifilm.com/support/digital_cameras/manuals/pdf/index/x/fujifilm_xe2_manual_en.pdf