• Number of trainers per page: Set how many trainers do you want to display per page.
• URL Rewrite: The text displayed in the URL when you view a single trainer page.
  

After changing this field go to Settings → Permalinks → Save Changes.

• Category URL Rewrite: The name displayed in the URL when you access the trainers archive, such as a trainers category.

After changing this field go to Settings → Permalinks → Save Changes.

Category URL Rewrite and URL Rewrite can’t share the same name

• Default Header Image: The header image to be displayed if a header image isn’t set for that specific post.