Xl macro

Hello,

Am new to macro i want someone to help me. I am haveing some data in the xl sheet1, the cell contains the combobox with values like

Combobox1 combobox2
Ram_kumar Air_force (each cell is combobox in that column)
Sasi_kumar Coast_guard (each cell is combobox in that column)
Jai_kumar Marine_crops (each cell is combobox in that column)

and a button on the sheet.

like this am having several combobox in my sheets. I have selected different values for each cell. Now if i click the button these values in the cell having Underscore("_") should be replaced with space(" ").

Note: The change should not happen in sheet1, it should happen with the sheet2