Today's awkward Japanese word is *drum roll please*:
Ah, the nuances of speech and context. 'Zenzen' is a tricksy one.
Use it with a positive, and it means 'totally' or 'completely'. But in that 'ohmigosh' slang-y way that most people find really irritating.
Use it with a negative and it means 'not at all', with emphasis. Like, no way, dude.
Use it without implying either... and it's more or less up to you.
Say 'zenzen daijoubu' (全然大丈夫), and you could be saying 'it's fine!' with a smile or 'it's FINE.' like a fed up and long-suffering romantic partner. BUT say 'zenzen OK' (全然OK) and there should be no doubt that things are hunky-dory. No hint of a lie or any sarcasm whatsoever.
A lot of people learn (or assume) that 'zenzen' is only negative. Or that 'zenzen' with positives is bad Japanese and should be avoided. I mostly hear 'zenzen' used on its own, as a way of saying 'don't worry about it'.
The second 'zen' (然) is meant to represent '-like' or 'in that way'.
It's used in these other words, both roughly meaning 'natural':
自然 - shizen
当然 - touzen
It's also in two kanji compounds identically pronounced 'kanzen':
間然 - liable to come in for criticism
敢然 - boldly (doing/saying something)
And then there are a bunch of words relating to 'inevitability' which I won't go into. Turns out 'zen' has many uses. I'd be here all day.
With the first 'zen' - 全 - generally meaning 'all/everything', it's simpler to see how the second 'zen' could make 'zenzen' positive or negative. Doesn't make it easier to use in conversation.
As an aside, I looked up some examples of positive 'zenzen' for you and all I'm getting is The Art of Zen. Is Google trying to tell me something?