Hi Kwok2,
I'm having trouble understanding what you are trying to ask. Are you asking how to display outputs from a subVI on the front panel? If those are outputs (and not inputs) then you can right-click on the terminal and Create->Indicator to display the values on the front panel. Is this what you are asking?
Travis H.
National Instruments
Travis H.
LabVIEW R&D
National Instruments