I split your new question into a new thread. Please review How to post a question on this MSOffice forum.

Jargon alert! See also What is the difference between headings and headers?
There is no Header 1 style in Word out of the box. You do NOT want to use the Heading 1 style in your header. There is a Header style. It may be that the computer icon cannot be shown at font size 10. You can change the font size of the Heading style to 11 and see if that helps.

The MERGEFORMAT switch is likely surplus and may be the cause of your problem.
The Difference between MergeFormat and CharFormat switches

Again, a sample DOCUMENT (not screenshot) would be useful.
How to attach a screenshot or file in this forum.