Option Explicit
Sub CommandButton1_Click()
Dim c As Range
For Each c In Selection.SpecialCells(xlCellTypeVisible).SpecialCells(xlCellTypeConstants)
If c.Value Like "*Ù*" Then
c.Interior.ColorIndex = 3
c.Replace What:="Ù", Replacement:="o", LookAt:=xlPart
End If
Next
End Sub