Graziese cerchi in rete ne trovi a centinaia di risposte
http://alessandro.dinoia.name/blog/2012/05/perche-i-preset-di-lightroom-3-non-funzionano-con-lightroom-4-e-come-resuscitarli/
http://blogs.adobe.com/lightroomjournal/2012/04/updating-develop-presets-for-lightroom-4-2.html
http://www.presetsheaven.com/tutorials/how-to-update-lightroom-3-presets-to-lightroom-4/
ciao