You should anchor the shape (or text box) to the first page header, not to a paragraph in the main body of the document.

In the attached document, I have done the following: First I cut the shape from the main body. Then I double-clicked the header area. After it got activated, I selected the "Different first page" option on the ribbon. I then pasted clipboard contents, saved and closed the file.

For more on letterheads, see the article that Charles linked to.

Attached Files

Revised Letterhead Red.docx (35.9 KB, 10 views)

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Stefan Blom
Microsoft Word MVP

Microsoft 365 apps for business
Windows 11 Professional