Command Button - Assign Macro

You can't really, everytime you copy or create a command button in excel, excel gives it a new name by incrementing the numeral after it, so, you physically have to assign the macro you wish to this button, however if you want the same button for each sheet why not put it on the toolbar then its visible and works the same for every sheet!

If you do not want to do this you could always create the button by macro everytime you activate the worksheet and have a macro assigned but its messy!