There are several possible reasons why the Sensor Dry cycle in your DV330 is not drying the clothes thoroughly. Please click on the link below then select "Troubleshooting ► > Clothing And Laundry ► > Clothes Are Damp At The End Of A Dry Cycle" for a list of suggestions: http://support-us.samsung.com/cyber...
If you'd like to use the Low heat setting for a Sensor Dry cycle, you can select "Delicates" rather than "Permanent Press" which is pre-set for Medium heat. Each cycle has its own pre-programmed settings; please refer to the Cycle Chart in the back of your User Manual for details.
To help prevent sheets from rolling up into balls, try adding a few towels to the dryer load. Three to four towels is usually sufficient.
Thank you for the questions!