Word of Recall.
"You must designate the sanctuary when you prepare the spell."
Now in most cases, I'd assume "prepare the spell" had to do with writing it into the scroll. However...
"Word of recall teleports you instantly back to your sanctuary when the word is uttered."
leads me to believe the spell doesn't trigger until the final trigger word is spoken.
Since it's a standard action to cast, I assume that means the preparing of the spell happens separate from the casting.
My gut would say that "Preparing a spell" happens normally when the caster is choosing spells for the day. It's a Cleric/Druid spell.
I'm really curious how a Favored Soul would use this spell.
...So I'd rule that my understanding of RAW means the scroll would be set by the preparer of the scroll. ...
But, since that most likely makes it useless, I'd say ignore the RAW ruling and play what makes sense- the possessor of the scroll stands in the designated Sanctuary, keys it to that location, then uses it later.