Why do someone see 4 attendes on their screen, and othe only 1?

Hi;

What is the reason for this? Do they uese differentr devices, or is it a setting? 

"We on the team keep in touch through teams and video call. Some of us get up four squares with little picture of each of the participants but others just get a big picture of one at a time. Then it changes based on who is talking."

- Geir