Dim strText As String

  strText = "Test-String " & String(300, "A") & " Test-String"
  ActiveDocument.FormFields("Text1").Result = strText

Sub Beispiel_1()
  Dim strText   As String
  Dim objFField As FormField

  strText = "Test-String " & String(300, "A") & " Test-String"
  Set objFField = ActiveDocument.FormFields("Text1")

  ActiveDocument.Unprotect
  objFField.Range.Fields(1).Result.Text = strText
  ActiveDocument.Protect Type:=wdAllowOnlyFormFields, _
                         NoReset:=True
  Set objFField = Nothing
End Sub

Sub Beispiel_2()
  Dim strText As String

  strText = "Test-String " & String(300, "A") & " Test-String"

  With ActiveDocument
    .Unprotect
    .Bookmarks("Text1").Range.Fields(1).Result.Text = strText
    .Protect Type:=wdAllowOnlyFormFields, NoReset:=True
  End With
End Sub

Option Explicit

Private Const mc_DocVarLineFeed As String = "LineFeed"

Private m_objDoc  As Word.Document

Private Sub UserForm_Initialize()
  With Me.txtTextfeld2
    .MultiLine = True
    .EnterKeyBehavior = True
  End With

  Me.cboDropDown.Style = fmStyleDropDownList
  Me.cmdOK.Default = True
  Me.cmdCancel.Cancel = True
End Sub

Private Sub UserForm_Activate()
  Dim strDocVar As String

  Dim objCtl    As Control
  Dim objFField As FormField
  Dim strName   As Variant

  Dim i         As Integer

  On Error Resume Next
  Set m_objDoc = ActiveDocument

  If m_objDoc.ProtectionType = wdNoProtection Then
    m_objDoc.Protect Type:=wdAllowOnlyFormFields, NoReset:=True
  End If

  strDocVar = GetDocVarValue(m_objDoc, mc_DocVarLineFeed)
  If InStr(1, strDocVar, "Absatz", vbTextCompare) Then
    Me.optChr13.Value = True
  Else
    Me.optChr11.Value = True
  End If

  For Each objCtl In Me.Controls
    If TypeOf objCtl Is MSForms.TextBox Or _
          TypeOf objCtl Is MSForms.CheckBox Or _
          TypeOf objCtl Is MSForms.ComboBox Then

      strName = objCtl.Name

      If m_objDoc.Bookmarks.Exists(strName) Then
        Err.Clear
        Set objFField = m_objDoc.FormFields(strName)

        If Err.Number = 0 Then
          Select Case objFField.Type
            Case wdFieldFormTextInput
              objCtl.Text = objFField.Result

            Case wdFieldFormCheckBox
              objCtl.Value = objFField.CheckBox.Value

            Case wdFieldFormDropDown
              Me.Controls(strName).Clear
              With objFField.DropDown
                For i = 1 To .ListEntries.Count
                  Me.Controls(strName).AddItem _
                        .ListEntries(i).Name
                Next
                Me.Controls(strName).ListIndex = .Value - 1
              End With

            Case Else
          End Select
          Set objFField = Nothing
        End If
      End If
    End If
  Next
  On Error GoTo 0
End Sub

Private Sub cmdOK_Click()
  Dim objCtl    As Control
  Dim objFField As FormField
  Dim strName   As Variant

  Dim strChr    As String
  Dim strText   As String

  If (m_objDoc Is Nothing) Then Exit Sub

  If m_objDoc.ProtectionType = wdNoProtection Then
    m_objDoc.Protect Type:=wdAllowOnlyFormFields, NoReset:=True
  End If

  On Error Resume Next
  If Me.optChr13.Value = True Then
    strChr = Chr$(13)
    m_objDoc.Variables(mc_DocVarLineFeed).Value = _
             "Absatzschaltungen"

  Else
    strChr = Chr$(11)
    m_objDoc.Variables(mc_DocVarLineFeed).Value = _
             "Zeilenschaltungen"
  End If

  For Each objCtl In Me.Controls
    If TypeOf objCtl Is MSForms.TextBox Or _
          TypeOf objCtl Is MSForms.CheckBox Or _
          TypeOf objCtl Is MSForms.ComboBox Then

      strName = objCtl.Name

      If m_objDoc.Bookmarks.Exists(strName) Then
        Err.Clear
        Set objFField = m_objDoc.FormFields(strName)

        If Err.Number = 0 Then
          Select Case objFField.Type
            Case wdFieldFormTextInput
              strText = objCtl.Text

                If InStr(1, strText, Chr$(13) + Chr$(10)) Then
                  #If VBA6 Then
                    strText = VBA.Replace(strText, _
                                  Chr$(13) + Chr$(10), strChr, 1)
                  #Else
                    strText = Replace(strText, _
                                  Chr$(13) + Chr$(10), strChr, 1)
                  #End If
                End If

                If Len(strText) > 256 Then
                  m_objDoc.Unprotect
                  objFField.Range.Fields(1).Result.Text = strText
                  m_objDoc.Protect Type:=wdAllowOnlyFormFields, _
                                   NoReset:=True

                Else
                  objFField.Result = strText
                End If

            Case wdFieldFormCheckBox
              objFField.CheckBox.Value = objCtl.Value

            Case wdFieldFormDropDown
              objFField.DropDown.Value = objCtl.ListIndex + 1

            Case Else
          End Select
          Set objFField = Nothing
        End If
      End If
    End If
  Next
  On Error GoTo 0

  Unload Me
End Sub

Private Sub cmdCancel_Click()
  Unload Me
End Sub

Private Sub UserForm_QueryClose(Cancel As Integer, _
        CloseMode As Integer)
  If (Not m_objDoc Is Nothing) Then
    Set m_objDoc = Nothing
  End If
End Sub

Private Function GetDocVarValue(ByVal objDoc As Document, _
      ByVal vsDocVar As String) As String

  Dim objDocVar As Variable
  Dim nIndex    As Long

  For Each objDocVar In objDoc.Variables
    If objDocVar.Name = vsDocVar Then
      nIndex = objDocVar.Index
      Exit For
    End If
  Next

  If nIndex = 0 Then
    objDoc.Variables.Add Name:=vsDocVar, _
              Value:="Absatzschaltungen"
    GetDocVarValue = "Absatzschaltungen"
  Else
    GetDocVarValue = objDoc.Variables(nIndex).Value
  End If
End Function