先找出底色代號
sub testcolor
MsgBox ActiveCell.Interior.ColorIndex
end sub

再改變顏色
sub changecolor
While ActiveCell.Value <> ""
If ActiveCell.Interior.ColorIndex = 38 Then
For i = 1 To 3
ActiveCell.Offset(0, i).Interior.ColorIndex = 8
Next
End If
ActiveCell.Offset(1, 0).Select
Wend
end sub