Yes, you can select or change your meal preferences as well as modifying your seat selection. You can change your selected seat anytime (subject to availability), while you can submit your special meal request at least 48 hours before the departure time of your flight. Please use this link to retrieve your booking and submit your requests
https://booking.qatarairways.com/nsp/views/retrievePnr.xhtml
To know more about our special meals menu, please visit our website
https://www.qatarairways.com/en/services-special.html