I Am Not "They"

I have only just noticed that Facebook, (where I am reading, sharing and liking but not posting for lent,) uses plural pronouns for me.
F'rinstance, "XXX changed their profile picture."
Is that because I needed to select from some long list of possibilities what "gender" I am currently "choosing"?
I am singular and female, but come April perhaps I'll do something silly - I've always liked the sometime-pretentious use of "one,"  or "ones" subbing for I/me/mymine... is that an option on FB?

I mean, now that feels trumps reals, and words have ceased to have meaning...