Option Explicit
Private Sub UserForm_Activate()
Dim ctl As Control, ratiow As String, ratioh As String
ratiow = Application.Width / Me.Width: ratioh = Application.Height / Me.Height
Me.Left = 0: Me.Top = 0
Me.Width = Application.Width: Me.Height = Application.Height
For Each ctl In Me.Controls
ctl.Left = ctl.Left * ratiow
ctl.Top = ctl.Top * ratioh
ctl.Width = ctl.Width * ratiow
ctl.Height = ctl.Height * ratioh
ctl.Font.Size = ctl.Font.Size * ratioh '*** Plante ici ***
Next
End Sub