I realise I'm replying to an answer given back in January, and I'm sure you're fully aware that this is not a 'fix' but instructions on how to do this in a fully working program.
I appeared here earlier on to say that hide the toolbar keeps switching off, so the toolbar doesn't hide. I have tried some fixes given here (not the coding one because I truly don't want to break anything else!)
After having experienced a half-full toolbar (ie icons missing) and toolbar stuck open so I couldn't remove it or otherwise stuck closed so I had to click windows key to reawaken, I decided to explore changing the setting in safe mode, as someone had deemed it a roaring success. Sadly, not so me. I've started the thing in safe mode, changed the settings, restarted, and guess what? - toobar setting is still on 'hide the taskbar', but when I hid it, it refused to come back without the windows key. So nothing's changed. Except it's worse. It still refuses to hide, yet when it does hide it seems permanently stuck in hide without the windows key.
Come on, Microsoft. It's been 4 long months now! Why did you tell me to take this devastating step? My win10 toolbar was almost perfect. It hid when not needed, I could miniaturise it, and if I really needed it out of the way, I could throw it to another side of the computer screen. If you were going to make drastic changes to the toolbar behaviour, you should have ensured it worked before foisting it onto your unsuspecting public. Any news about when this disaster is going to be put right, or should I simply rewind to windows 10 and have done with it? It's unbelievable how much time and frustration this has cost me in the last 4 months.