When the headrest is all the way up and I press the release button, the headrest slides down one notch at a time as it should. When I pull it up no release button is required. The headrest advances to the next notch until it reaches the last one. Way too loosely, though. Sometimes when turning around and lifting my head as I look back while parking in R causes me to rub against the headrest which then without intention slides up, blocking the view. I have not experienced this with any other car seat design. Maybe it's like this on all cars but the mechanism is much firmer and doesn't slide so easily?
I drove a rental Kia something or other that did this. It also was labeled as having "active head restraints" that positioned the headrest very close to my head, making it even more annoying. I'm thinking that antimacassars might be coming back in style.
I'm 6'2 and I also find my driver side headrest raising up a few notches after I've pushed it all the way down. Obviously, the extension detents are not deep enough. Also, I wish I could lower my headrest a couple notches more than it goes, but oh well, that's how it is... Happy Motoring, Tom