How do I change the answers to the export compliance questions in iTunes Connect?
Either uploading a new binary update or rejecting the App's actual binary and then pressing on Ready to Upload Binary should do the trick.
As written under Apple's iTunes Connect Guide:

Cryptography and U.S. Export Compliance
U.S. export laws require that products containing encryption be properly authorized for export. When you’re ready to upload your first binary for your app or upload a binary update, iTunes Connect presents a series of questions regarding software encryption. The questions are designed to determine the level of encryption in the app according to U.S. Bureau of Industry and Security (BIS) classifications.