Which word do you use?
Growing up, we used to say settee, but at some point, we switched to sofa. I'm a Londoner, but my mum was from the Midlands, so I think that was a regional thing we got from her.
It looks strange too. Interestingly enough, I believe the stress is on the second syllable, but I sort of remember, and this was like 30 years ago, that in my house we said it with the stress on the first syllable, sounds less posh that way.
I don't think I've met any other people who call it settee outside my family years ago.