1. Go to Communities > Forms > Registration
2. Hover over your Event or Registration Form name
3. Click Website Info
4. Click Registration Form Options
5. Click Next until you reach Email Confirmation - Step 5 of 5
6. Click on Advanced Confirmation Setup
7. Click the Edit link next to Registration Confirmation
8. Click the Edit Email link under Use Customized Text
9. Click the yellow and red Dynamic Content (abbreviated DC) can
10. In the first dropdown menu, select Registration Type
11. In the second dropdown menu select the desired registration type
12. Click the Create link next to THEN DISPLAY CONTENT
13. Type a name for the content into the text box, and click Submit
14. In the window that pops up, enter the content you would like to have appear for the selected registration type
15. Press Save to apply these changes
16. Press Finish to dismiss this window
17. Click Add
18. Repeat steps 12-17 for all registration types
19. Click Submit
20. Press Save on the Confirmation Editor window
21. Press Return to the setup page
22. Press Save
 
This should apply these changes.
 
Register for the event to test the confirmation email and confirm everything is working properly.