so when i watch eng sub korean dramas and they mention money im always confused whether they are talking about the money in USD or Korean won

I think often subbers do the quick and dirty conversion of won to USD: 1000 won is $1.  Next time I should listen more carefully and see what they say, haha.  It shouldn't be that difficult to figure out since I know numbers in Korean, at least.

Are you thinking of a particular case?  Or have you seen something where they just use a number and no unit?  Because I think usually if the subs say "x won" then that's what it means, or if "x dollars" they converted it...or I should hope so.  I've seen both used, but usually there's a unit.

I would prefer original currency. If they talk about won then in subs should be also won. Or at least it should be consistent during a drama. Sometimes subs write about e.g. 10 million won and later about $10 000. Or we can see in a movie that a calculation of something is done in won and subs write it in dollars. It is confusing.

I also think that the people who do the subs do the conversion to USD

Yea, I realize that $1 is roughly 1000 ₩ , so when they have to pay like 50,000 ₩  at a coffee shop I can easy see it's about $50.

I don't know which I prefer to see in subtitles, the ₩ amount or $ amount. At least for lower amounts I'm okay with ₩  amounts, but when they start talking in billions and billions I just lose track and it's easier for me to understand in $ terms.