Syncing an iPod with iTunes is necessary to add music to or delete music from an iPod. When you attempt to sync the same iPod with a different version of the iTunes software, however, you run the risk of accidentally erasing the entire content library on that iPod. In order to avoid this from occurring, you will only need to make one change to the sync settings on that iPod using the iTunes software.
Plug the iPod you want to sync with iTunes into a USB connection for the computer.
Close the window that opens in iTunes by clicking on either the “X” button or the “No” button. If no window opens, however, you can safely proceed to the next step.
Click on the link for the iPod that was plugged in located underneath “Devices.”
Select the tab named “Summary” at the top of the main iTunes window. Four different settings for the iPod will appear in the bottom of iTunes.
Click on the box found to the left of “Manually manage music and videos” to enable that setting.
Click “Apply” to save the “Manually manage” setting on the iPod. You will now be able to sync that iPod without iTunes automatically erasing the library on the device.
iTunes 9.0.3. was used in this piece.