By default, speakers appear in the order they were added to the session.
If you want to change that order, simply use the little drag tool next to the recycle bin icon that appears when hovering over the profile to move speakers up or down the list. This is found under "Content > Sessions," session concerned, Tab 3 "Speakers."
Your speakers can have different types as well. You can simply reorder them under "People > People Settings > Type." Move values up/down as needed by pressing down on the value.