You can edit the photos on your job posts by:
1. Visiting your Dashboard
2. Click the 'Manage Postings' link in the left menu
3. Click the name of the post you want to edit
Photos are either a part of the Team Story page (in which they are the same for all of your postings), or the Job page (specific to that one post).
If you are still having trouble, contact Wantedly Customer Relations Team from here!
Sorry for the inconvenience :(