Once your group has completed pairings, if two players need swapped from group to group, this is the function you use. From the pairings screen you will see two buttons at the bottom:

Remove Player

Swap Players

We have another help article about removing players here.

To swap players, click the button

This brings up the swap players icons next to each player. Select the player you want to swap to another team.

You will then be directed to the next team you can choose from. You can scroll through the teams at the top to find the player you want to swap. Choose them and click "Done".

You will now see that the players have been swapped and you can now swap other players or leave the screen.