Click the Options Menu, Certifications/Payments to access Payments/Unpaid Certifications.
Use the Fund Slider to select the Fund in which you want to work.
Click the Certifications (Payment Not Allowed) Tab.
Select the Certification you want to edit. The selected Certification is highlighted in blue.
Click 
.
The Certification Form will appear:
Check the Allow Payment Check Box.
Click 
.
NOTE: This will move the Certification to the Certifications (Payment Allowed) Tab.