1080x1080 px is a rectangle?

[justsomeonehere]

Hello, I'm rather new to Adobe After Effects. For some reason, when I put the composition width and height to 1080x1080 px (which is supposed to be a square, from what I heard) it turns into a rectangle. I'm using Adobe After Effects 2020. 

[Rick Gerard · Accepted solution]

You have set a custom pixel aspect ratio. Check the composition settings carefully.

[justsomeonehere]

Thank you very much!