Automatic synchronization
To change the default file transfer option in Windows
Media Player, click the arrow under Sync, select your
device, and click Set up Sync. Clear or select the Sync this
device automatically check box.
If the Sync this device automatically check box is selected
and you connect your device, the music library in your
device is automatically updated based on playlists you
have selected in Windows Media Player.
If no playlists have been selected, the whole PC music
library is selected for synchronization. Note that your PC
library may contain more files that can fit to the device
memory and the compatible memory card of your device.
See the Windows Media Player help for more information.