When adding speakers to the sessions, the order in which they appear will be displayed in the Schedule tile to all participants in the Web App (next.brella.io).
How to change the order
Go to the event at https://manager.brella.io
Go to the "Schedule" from the Content tab
Click "Edit" in the selected session
Click "Speakers"
Click on the dots, drag and move the speaker, and click on update
The speaker order will be updated in the session.