I have to manually change the songs on my ipod

If you want iTunes to automatically update your iPod with the same changes you make to your iTunes Music library, your iPod's storage capacity must be large enough to hold your entire Music library. If that's the case, you can do the following.

Select iPod in iTunes, so that you see its settings screen. In the sidebar, along left side of window, under Settings, click Music. To the right, you see iPod's Music settings screen, where you tell iTunes how to automatically sync iPod with songs.

NOTE: Do not proceed if there are songs on iPod that are not in your iTunes library (on computer). Any songs on iPod that are not in your iTunes library will be lost.

Checkmark the box for Sync Music, at the top. Just below that, select the option to sync Entire music library. At the bottom, click the Apply button. This may take some time; iTunes is replicating your iTunes Music library on your iPod, with all songs and playlists. Going forward, when you connect your iPod (or click Sync if already connected), iTunes automatically updates iPod with changes.

If your iPod cannot hold your all of you music, there are other automatic loading methods. You can post back for more info.