Screen Mirroring Separate Displays

Hello, I was using a projector by screen sharing my MacBook. I used the 'Use as a separate display' option, and I accidentally switched my main screen (my MacBook) and the second screen (my projector). Now, whenever I screen share with that projector, all my tabs are stuck to the projector since it is the main screen. How do I switch them back?

Thank you in advance.