2 Answers
To answer your first question, when you click on the DynamoDB service under the Services tab, there’s a hamburger menu that expands on the left side that has "Dashboard", "Tables", etc. listed. Near the bottom of the menu items is "Return to the previous console experience", click it and it’ll revert the UI to the previous look before the most recent update.
Could anyone answer the second above mentioned queastion regarding sandBox and DynamoBD Repliation?