Allow participants to edit their Personal page headers requires a setting to be enabled under Image and Text Library for Page Customization. 

How to enable 
  1. Navigate to Communities > Special Events > Friends Asking Friends > Kintera Thon
  2. Hover over the event name and click on Website Info
  3. Click Image and Text Library for Page Customization
  4. Select Personal Page Text Library from the "Select the area to customize" drop-down menu
  5. Mark the checkbox next to: Allow participants to edit image captions and page text in their personal and team donation pages.
  6. Click Save
  7. Navigate back to the Webinfo Checklist and Publish This Event Now

Note: This change is retroactive for participants.