ChangePropText

Private m_Text1_Appearance As Long
Private Sub Form_Load()
    With Text1
        Picture1.Width = .Width
        Picture1.Height = .Height
        .Move 0, 0
    End With
    Text1_Appearance = 1  '3D
End Sub

Public Property Let _
        Text1_Appearance(nAppearance As Long)
    With Picture1
        Select Case nAppearance
            Case 0  'Flat
                .BorderStyle = nAppearance
            Case 1  '3D
                .BorderStyle = nAppearance
        End Select
        m_Text1_Appearance = .BorderStyle
    End With
End Property

Public Property Get Text1_Appearance() As Long
    Text1_Appearance = m_Text1_Appearance
End Property

Sorry, you can't change the Appearance property of a text box 
at run time-but you can make it look like you have! If set to 
none, a 3-D picture box has a flat BorderStyle property. Put 
your text box (with a flat appearance) inside a picture box
(with a 3-D appearance) and change the picture box's border 
style. Use this complete code-be sure you place Text1 inside 
Picture1:

Private m_Text1_Appearance As Long
Private Sub Form_Load()
With Text1
Picture1.Width = .Width
Picture1.Height = .Height
.Move 0, 0
End With
Text1_Appearance = 1 '3D
End Sub

Public Property Let _
Text1_Appearance(nAppearance As Long)
With Picture1
Select Case nAppearance
Case 0 'Flat
.BorderStyle = nAppearance
Case 1 '3D
.BorderStyle = nAppearance
End Select
m_Text1_Appearance = .BorderStyle
End With
End Property

Public Property Get Text1_Appearance() As Long
Text1_Appearance = m_Text1_Appearance
End Property

Sorry, you can't change the Appearance property of a text box
at run time-but you can make it look like you have! If set to
none, a 3-D picture box has a flat BorderStyle property. Put
your text box (with a flat appearance) inside a picture box
(with a 3-D appearance) and change the picture box's border
style. Use this complete code-be sure you place Text1 inside
Picture1: