Currently due dates turn yellow the day before, and red the day of. Can I change this so that they turn yellow, say, a week before, and red a few days before? A day is often very short notice :)
The answer is no, according to their card guide on Due Dates:
You can set a date and time for when a card is "due". A badge with the due date will appear on cards. A yellow badge means it's within 24 hours of being due A red badge means it's past due.
I would suggest emailing their support team to suggest a feature.