Did you cash out any amount? Or did you refi "ONLY" what you owe on the original loan?
If you did not take any cash out during the refinance and this was your original loan then you would say Yes, all of your loan proceeds were used to buy, build or substantially improve your home.
If you took any cash out at all, then you would say No, it was not all used to buy, build or substantially improve your home.
What box? When asked the question about taking a cash out, you should have answered that question as no. You may need to work back through it again.
During the interview, the program will ask