Firstly, writing to bookmarks is non-intuitive because the added text is beside the bookmark rather than inside it. This means it works once but a second pass with the macro adds a second copy instead of replacing. You get around this shortcoming by redefining the bookmark range after writing the text. See
https://www.msofficeforums.com/word-...lues-text.html for an example of this.
If you want to show/hide a range based on a checkbox, you can do it without an If statement
Code:
' Hide the text if checked, show if unchecked
ActiveDocument.Bookmarks("ContinenceCost").Range.Font.Hidden = ContinenceCB
'or vice versa
ActiveDocument.Bookmarks("ContinenceCost").Range.Font.Hidden = Not ContinenceCB