You don’t need to press any keys, just move the mouse to the blank space next to the song number, hold down the left mouse button and drag it up or down. If you want to order certain songs, those songs are not together. Then, hold down the CTRL key and click on the songs you want to select one by one until the selection is complete. You can release CTRL on the way, but don't click on the song when you release it. Just keep holding CTRL when you want to select.