There seems to be a lot of confusion about how setting the Front Comand Dial works on the X-H2S.
The Front Command Dial settings are different for each shooting mode (P/A/S/M), and you need to set them for each mode independently..
The camera will not let you change a setting that is not available in the mode you are currently using. e.g., if you are in mode A, you can't set the Command Dial to Shutter Speed, because Aperture Priority means that SS is being selected automatically be the camera.
It can get kind of tricky pickiing what you want to assign to each slot in order to stay consistent across the modes. Mode P only gives you Program Shift and EC as options, but I don't use P, so I don't care. In A, S & M, I assign F to 1, ISO to 2, EC to 3 and SS to the rear dial. When a setting is not available for the mode, you can set the position to "None" for consistency, orif you prefer, to whatever is available, for convenience.