Sub Macro1()
Dim Sht As Worksheet
For Each Sht In ThisWorkbook.Sheets
With Sht.Range("A1:A100").Validation
.Delete
.Add Type:=xlValidateList, AlertStyle:=xlValidAlertStop, Operator:= _
xlBetween, Formula1:="Toto;Tata;Titi"
.IgnoreBlank = True
.InCellDropdown = True
.InputTitle = ""
.ErrorTitle = ""
.InputMessage = ""
.ErrorMessage = ""
.ShowInput = True
.ShowError = False ' Ne pas oublier
End With
Next Sht
End Sub