If you want to make changes to your flight tickets then you have to pay the Etihad airways ticket change fee. Ticket change charges will depend on many factors: Tickets change fee will depend on route and fare. If you are changing your flight ticket in 96 hours then you have to pay 10% additional charges. If you are making changes after 24hours then you have to pay the Etihad change fee.

https://airlinespolicy.com/flight-change-policy/etihad-airways-flight-change-policy/