Sometimes you need to make changes in a Workspace. It's easy.
Brush up on workspaces with Understanding Workspaces and Person Partitions.
Under Admin, click on Workspaces & Partitions.
Select the workspace you want to edit and click on Edit Workspace.
You can select a different lead partition and choose a different primary person partition from the drop-down.
If you enabled multiple branded domains, you can change to a different primary branded domain. Click Save.