Easiest thing would probably just be to put your current sd card in your PC, highlight and copy everything, and then paste it onto the new card. Depending on how you set up your phone, we don't know which apps or data you have running on the external or internal, etc. Basically if you want to switch cards without any hiccups it's best to just assume whatever is on the old card should go on the new card so the phone can find everything in the same place.