Je te propose cette petite macro :
Option Explicit
Private Sub Worksheet_SelectionChange(ByVal Target As Range)
Dim i As Integer, j As Long
Dim nC As Integer, nL As Long
Dim wS As Worksheet
Set wS = ActiveSheet
nL = wS.UsedRange.Rows(wS.UsedRange.Rows.Count).Row
nC = wS.UsedRange.Columns(wS.UsedRange.Columns.Count).Column
' On retire toutes les couleurs de la plage
Application.ScreenUpdating = False
For i = 1 To nC
For j = 2 To nL
Cells(j, i).Interior.ColorIndex = 0
Next j
Next i
' On Colorise les cellules
For i = 1 To nC
For j = 2 To nL
If wS.Cells(j, i).Value <> "" Then
If wS.Cells(j, i) = Target.Value Then wS.Cells(j, i).Interior.Color = RGB(255, 255, 0)
End If
Next j
Next i
Application.ScreenUpdating = True
End Sub