How do I set the remaining number of reader spots?

You can set the number of remaining reader spots on a book by book basis:

1. Go to your books.
2. Click Edit next to the book you're interested in.
3. Click the Readers tab. 
4. If you're promoting your book to our community, you'll now see two tabs: Readers We Find and Readers You Invite. Make sure you select the one you wish to change as they're completely independent.
5. Set the Reader Spots Left to the number you wish. If you wish to add more spots, set the number to a greater value than what you see. If you wish to reduce the number of spots, set the number to a lesser value than what you see. If you want to prevent any more readers from downloading your book, set it to zero. You can come back and add more spots later by following the same steps.
6. Click Update.