Yes. Confirmed bookings are eligible for changes unless otherwise stated in the fare terms and conditions.
Bookings made through qatarairways.com, Qatar Airways ticketing offices and Qatar Airways airport ticketing can be changed online, over the phone or at Qatar Airways ticketing offices.
To change a booking made with a travel agency or a travel website, contact the travel agency/website.
For assistance contact your local offices, contact details can be found in the following link https://www.qatarairways.com/en/worldwide-offices.html