If you go to the Windows tab under the Settings/preferences click on Preferences and then UI Elements, scroll to Panel Configurations and On new scene uncheck reset viewport panel settings, It will keep the Legacy setting you set until you manually change it.

For interactive creation look under the Create menu set and in the Objects section you can check or uncheck as needed Interactive Creation at the bottom of both the Nurbs Primitives and Polygon Primitives fly out menus.