To change seedings, click on the Sort Item button. It will change color and read Sorting Item. Use the Blue Up and Down Arrow Buttons on the right to move the team.
Click on the Sorting Item button again when the team is correctly placed.
The team will be in their new position but the original seed, shown by the red arrow, will still show. Press the green Save button to save your changes. The team will then be locked in the new position and the new seed number will show.
You can also drag and drop the team into the new position on the seeding list.