Brandon pre-signs all books sold in the store, rather than signing them at the time they are purchased. Personalizations are not available due to Brandon's focus on the leatherbound signatures, tip-in pages, and (most importantly) writing more books for you!
Check out his YouTube channel to see livestreams where he signs pages and books and interacts with fans. Catch him live to ask your questions—who knows, he may answer you on the stream!
Try to catch Brandon at a convention or other in-person event and have him personalize your book there.