Ralf999,

The following is a mult-ifile multi-word find and replace anywhere macro.
You should be able to extract the code you need from here:

Public Sub BatchFileMultiFindAndReplace()

'This macro is a collection of work by Doug Robbins, Peter Hewett, Klaus
Linke, Graham Mayor and and a little bit by me, Greg Maxey

Dim myFile As String
Dim PathToUse As String
Dim myDoc As Document
Dim rngstory As Word.Range
Dim ListArray
Dim WordList As Document

'Close any documents that may be open
If Documents.Count > 0 Then
Documents.Close SaveChanges:=wdPromptToSaveChanges
End If
' Change the path and filename in the following to suit where you have your
list of words
Set WordList = Documents.Open(FileName:="D:\My Documents\Word\Word
Documents\Word Tips\Find and Replace List.doc")
ListArray = WordList.Tables(1).Range.Text
ListArray = Split(ListArray, Chr(13) & Chr(7))
WordList.Close
' Get the folder containing the files
With Dialogs(wdDialogCopyFile)
If .Display <> 0 Then
PathToUse = .Directory
Else
MsgBox "Cancelled by User"
Exit Sub
End If
End With

If Left(PathToUse, 1) = Chr(34) Then
PathToUse = Mid(PathToUse, 2, Len(PathToUse) - 2)
End If

myFile = Dir$(PathToUse & "*.*")

While myFile <> ""
'Open each file and make the replacement
Set myDoc = Documents.Open(PathToUse & myFile)
'Fix the skipped blank Header/Footer problem
MakeHFValid
'Iterate through all story types in the current document
For Each rngstory In ActiveDocument.StoryRanges
'Iterate through all linked stories
Do
SearchAndReplaceInStory rngstory, ListArray
' Get next linked story (if any)
Set rngstory = rngstory.NextStoryRange
Loop Until rngstory Is Nothing
Next
'Close the file, saving the changes.
myDoc.Close SaveChanges:=wdSaveChanges
myFile = Dir$()
Wend

End Sub
Public Sub SearchAndReplaceInStory(ByVal rngstory As Word.Range, ByRef
ListArray As Variant)
'This routine supplied by Peter Hewett and modified by Greg Maxey

Dim Source As Document
Dim i As Integer
Dim Find As Range
Dim Replace As Range
Set Source = ActiveDocument
Source.Activate
For i = LBound(ListArray) To UBound(ListArray) - 1 Step 3
 With rngstory.Find
   .ClearFormatting
   .Replacement.ClearFormatting
   .Text = ListArray(i)
   .Replacement.Text = ListArray(i + 1)
.Wrap = wdFindContinue
.Format = False
.MatchCase = True
.MatchWholeWord = False
.MatchAllWordForms = False
.MatchSoundsLike = False
.MatchWildcards = False
.Execute Replace:=wdReplaceAll
End With
Next i
End Sub
Public Sub MakeHFValid()
'And this too
Dim lngJunk As Long
' It does not matter whether we access the Headers or Footers property.
' The critical part is accessing the stories range object
lngJunk = ActiveDocument.Sections(1).Headers(1).Range.StoryType
End Sub.

See the article "Using a macro to replace text where ever it appears in a
document

including Headers, Footers, Textboxes, etc." at:

http://word.mvps.org/FAQs/Customization/ReplaceAnywhere.htm

Dear Sirs,

I tried both of your proposed methods but I guess I am not skilled
enough to implement it...

Greg: I used your VBA. For the information to be searched and replaced,
I have a word-file, which contains a table with the expression in the
left column to search and the expression (with spaces between) to
replace with. But he is not reading the information. Do I need to
organize it in a different way?

Doug: Thank you for the link. I read it but how can I make him replace
multiple expressions with other expression?

I am very grateful that you help me guys!

Thanks,

Ralf

Dear Sirs,

I tried both of your proposed methods but I guess I am not skilled
enough to implement it...

Greg: I used your VBA. For the information to be searched and replaced,
I have a word-file, which contains a table with the expression in the
left column to search and the expression (with spaces between) to
replace with. But he is not reading the information. Do I need to
organize it in a different way?

Doug: Thank you for the link. I read it but how can I make him replace
multiple expressions with other expression?

I am very grateful that you help me guys!

Thanks,

Ralf