Q&A for How to Transfer Your iTunes Library from One Computer to Another

Once you purchase the music you have the right to transfer it, as long as it's through iTunes. I wouldn't recommend USB transfer, but if it's for personal use then it doesn't matter -- do whatever you want.

Use a USB flashdrive or an SD Card. Insert the storage device and open the device's folder and the folder containing the songs; drag the songs from the song folder to the device folder. Remove the storage device and insert it into the new computer; open its folder and the folder where you will add these songs. Move the files like you did before.

Once you've selected all the files you want to copy to the second computer, scroll the page down and the import button is at the bottom of the screen, in the lower right hand corner.

Sync your iPhone with iTunes. However, music that already is on your iPhone will be removed if you use a different computer to sync after you have synced with the first computer.

This method works for things bought on iTunes as well as music bought elsewhere. I'd bought and downloaded CDs onto my old laptop, and after doing this, I was pleased to see that all of my music was there, including the stuff from the CDs.

If the music is stored on a USB ,you must open iTunes, then play the song from the file on the USB. This will then open in iTunes and you will no longer see the pop up that says iTunes could not locate the song.