I have found a lot of incidences of this problem going back as far a six years. I have read every post I could find and tried all of the proposed solutions that seemed to relate to my problem.
When I try to change the header image I get the following error message:
The uploaded file could not be moved to /home/httpd/vhosts/deltaforge.com/httpdocs/wordpress/wp-content/uploads.
I have tried changing permissions to all different levels. The most liberal of which is 777 and which should allow uploading by the group. I have made sure that I am the owner of the image file. I am able to upload manually to wp-content/uploads with FTP so I don't think that this is a server issue. I'm about ready to give up and reinstall WP unless someone has a better idea. (which I hope is the case).