Copa Airlines, like many other airlines, typically allows passengers to make changes to their flights within 24 Hours of booking without incurring change fees. This is in accordance with the U.S. Department of Transportation's regulations, and many airlines follow similar policies.

Check the Time Frame: Ensure that you are within the 24-Hour window from the time you made the original booking.
Visit Copa Airlines Website: Go to Copa Airlines' official website and locate the "Manage Reservations" or a similar section.
Enter Booking Information: Enter your booking reference number and the last name of the passenger to access your reservation.
Select Change Flight: Look for the option to change your flight. If you are within the 24-hour window, you should be able to make changes without incurring additional fees.
Follow Instructions: Follow the on-screen instructions to select a new flight that meets your requirements.
Review and Confirm: Review the changes you've made and confirm the new flight details. Make sure to check if there are any fare differences that may apply.
Payment: If there are any additional charges due to a fare difference, you may need to pay the additional amount.