IntelliSense in Visual Studio Code

Hi
I'm using VS code as unity C# editor and have problem with IntelliSence (which I really need, not being a programmer).
I've followed this https://code.visualstudio.com/docs/other/unity, installed all the plugins necessary, but the IntelliSence does not work properly. It "whispers" some commands, but some not. (see attachment as example)
For example, I'd like to declare gameObject by using "public GameObje..." declaration. I would expect that it will offer "GameObject" as one of the possibilities but it does not.
I have such issues every time I install Unity and VS code anywhere, on some decvices, I soved it out by combination of plugins and settings, but on other PC it does not work even though it seems the config is the same.
So what should I install/configure? Is there any WORKING howto?

thanks a lot in advance