Click on Backgrounds
Click on Options
Click on the background you want to use
Check the box under the preview monitor to Override Global Options for the Background
Click on the Background Designer button
When you click on the background in the Background Designer an outline will appear, allowing you to resize and move the text box.
This function is also available when editing a song. Just click in the preview window on the right of the song editor. You will then see the borders of the text box that allow you to change the text location. You may also access the background designer from the background menu in the song editor via Background Options.