If, in Setup, a card that references the current quest like Cold From Angmar is revealed, what quest does it affect? The main quest, a quest of my choice (if there is another quest), or none at all?

If, in Setup, a card that references the current quest like Cold From Angmar is revealed, what quest does it affect? The main quest, a quest of my choice (if there is another quest), or none at all?

It would affect the main quest. I recognize there is some ambiguity with the text below, but I think it is supposed to mean that the main quest is supposed to be the "current quest" by default.

At the beginning of each quest phase, if there are one or more side quests in the staging area, the first player may choose one to be the “current quest” until the end of the phase instead of the quest card that is currently active via the quest deck .

Pretty sure it affects a side-quest if one is active (thus current).

For comparative purposes look at the recent FAQ which has errata´ed "Devilry of Saruman" so it now uses the wording "main quest" as opposed to "current quest"

But set-up hapens before you can choose a side quest, so I guess it would, by default, go to the main quest. BTW, that treachery s.u.c.k.s.

The situation that Kakita Shiro mentioned is at setup, so before you are able to choose a sidequest.

so it attach to the main quest and it makes all its effects, in my opinion

It 100% attaches to a side quest if that side quest is the "current quest".

If it appears during setup its definitely going to go on the main quest by default though.

But set-up hapens before you can choose a side quest, so I guess it would, by default, go to the main quest. BTW, that treachery s.u.c.k.s.

No. that treachery is my best friend for getting Saruman remain in play!