Without seeing your updated code - especially for the font - it's impossible to know what the issue is. That said, the way you're adding content to the bookmarks means that you can't format the added content. For code to update a bookmarked range so that the update is accessible via the bookmark, try:
Sub Procedure1()
Dim objWord As Object, objDoc As Object
Dim ws As Worksheet
Set ws = ThisWorkbook.Sheets("Sheet6")
Set objWord = CreateObject("Word.Application")
objWord.Visible = True
Set objDoc = objWord.Documents.Open("C:\Users\Christopher.Ellis\Test1.docx") ' change as required
Call UpdateBookmark(objDoc, "CN1", ws.Range("C25").Text)
Call UpdateBookmark(objDoc, "CN2", ws.Range("C25").Text)
Call UpdateBookmark(objDoc, "CNo1", ws.Range("C26").Text)
Call UpdateBookmark(objDoc, "Cl1", ws.Range("C27").Text)
Call UpdateBookmark(objDoc, "Ex_1", ws.Range("C28").Text)
Call UpdateBookmark(objDoc, "Ex_2", ws.Range("C28").Text)
objDoc.Close True
Set objDoc = Nothing: Set objWord = Nothing: Set ws = Nothing
End Sub
Sub UpdateBookmark(objDoc As Object, StrBkMk As String, StrTxt As String)
Dim BkMkRng As Object
With objDoc
If .Bookmarks.Exists(StrBkMk) Then
Set BkMkRng = .Bookmarks(StrBkMk).Range
BkMkRng.Text = StrTxt
.Bookmarks.Add StrBkMk, BkMkRng
End If
End With
Set BkMkRng = Nothing
End Sub
Bookmarks