Assign participants to each breakout room if you didn't do so automatically or need to reassign someone to another room.
Note: Currently, people who join the meeting using PSTN or Teams devices can't be assigned to rooms. Use the main meeting as a breakout room for these people instead.
In the meeting controls, select Breakout rooms
.Select Assign participants. From this window, sort people to see who's been assigned where by selecting the down arrow next to Name or Room.
Choose the people you want in a room by selecting the checkboxes next to their names.
Select the down arrow next to Assign and choose a room for them.
Repeat the previous steps until everyone in the meeting is assigned to a room. When you're done, select Confirm.
If someone joins the meeting late, select Assign participants again to assign them to a room.