I don't usually do business tip posts on this blog, but it took me so long to figure this out, and I encountered so many people along the way who said, "Gee, I don't know, but will you let me know if you find it?" that I decided it was worth a simple, illustrated tutorial.
If you're a seller and you want to add a survey, gift options, or mailing list subscription to the PayPal checkout page your customer sees, here's how you do it.
After logging in, hover on the Profile link and choose More Options:
Select My Selling Tools:
Select Update on Custom payment pages:
Click on the Options tab:
Voila! Make your changes and save: