Content can only be reused if:
The content is a standalone learning item (documents, interactive files, videos and weblinks)
Created in your portal / available on your portal
It does not have a price. Premium subscribers can re-use Premium interactive files as they are 'free' given your subscription.
Editing courses:
Only Portal Admins, Content Admins can edit any courses that are created on their portals
Course Authors can only edit their courses
Search for your standalone resources
Using the search bar on the right-hand side of the page
See the results that are returned
Select the plus to add the result in the course structure
User can drag and drop the existing contents to the course structure and place it in the desired modules and positions
You can also search via the recent, popular, suggested.
You can search existing resources, in the same way you'd create a course. Search the title and select from the existing resources.