Navigate to the bracket channel that you want to rearrange seeding for. Select Edit seeding at the top to open Bracket settings.
Once in Bracket settings, in the Teams section select Shuffle seeds to randomly shuffle seeding. Alternatively, you can manually assign seed numbers to each team by clicking the icon to the left of Seed # and dragging the team to the desired order.
Once you have achieved your desired seeding arrangement, click Save changes.
Your new seeding arrangement will show up in the bracket channel. Finalize the bracket by clicking Start at the top of the screen to lock in seeding and begin the round. After brackets are finalized and rounds start, seeding can no longer be rearranged.