Don't know how to deal with teens who treat adults like they're friends

I'm a high school counselor for seniors (17 and 18 year olds) I do online video calls for my kids who need me. Although they're not blatantly disrespecting me, I truly hate how they talk to adults as if they're friends or on the same level. Some of them don't address me as Ms. Cordova but just "Cordova" or C. They don't say ma'am, they don't greet me formally but instead with something like "Hey" or "what's up." When one of my kids was talking to me about something they started with "Okay but this stays between us" Like, who are you talking to? And then they like to try to crack jokes with me and ask me personal questions. I try not to let any of this bug me because all of my kids are really good- I just wonder when parents stopped teaching kids to stay in a child's place.