Qatar Airways Flight Change policy allows passengers to change their flight date, time, and destination with or without additional charges, as long as the flights are within the same calendar year.

Qatar Airways Flight Change: Rule
The following Qatar Airways Flight Change rules will apply to all tickets issued up to August 31, 2021, for travel up to May 31, 2022:

You must complete your travel by May 31, 2022, to enjoy a rebooking fee waiver. Changes to dates and routes must be made before your flight’s scheduled departure time.
You must rebook on the same fare class as your original ticket to not pay extra.
Same-day date changes are not allowed.
If you’re changing your route, you must pay the fare difference, along with any tax, fee, or surcharge differences that apply.
Tickets booked directly with Qatar Airways can be changed online or by phone through a Qatar Airways contact center.
Tickets booked through third parties can only be cancelled through them.
If you’re flying to Australia, you must make the changes at least 3 days before your travel date. Name changes are not permitted.