[Element]

from media player help:
To switch between automatic and manual sync
After you've set up a device, you can switch to a different sync method at any time. Here's how:

Turn on your device and connect it to your computer.

In Windows Media Player, click the arrow below the Sync tab, point to the device, and then click Set Up Sync.

Clear or select the Sync this device automatically check box.

Do one of the following:

If you are switching to automatic sync, choose the playlists that you want to sync automatically. For more information, see "To choose what syncs automatically" earlier in this topic.

If you are switching to manual sync, choose the files or playlists that you want to sync manually. For more information, see Sync manually in Windows Media Player