@Stephen1002 I don't think we can change it... think it comes as standard for everyone who signs up! When I joined in Feb 2017, we all got "Hey, I'm......" - Now it's changed to "Hi, I'm....." I never noticed when it changed, & I read profiles daily, mine & guests! (& local rivals'!)
The OP was from 2016, & I see he had 1 host & 1 guest review from then, but nothing since so he no longer cares!
Airbnb support have nothing to do with this forum, so won't see your question! Phone them, or message via the 'help' tab on your account, if you feel strongly.... I'm sure it can't be changed tho'.... remember Airbnb is a San Francisco company, not British, so the "Hi ,I'm...."could be a 'normal' American thing....? - I rather liked the old "Hey, I'm....." - Made me feel young! - & hip! - Or whatever word they use these days!