The problem here is that when you recorded, you recorded in 4:3 (you can see on the export window that the original dimensions were 320x240), and so you would have positioned the text accordingly for that aspect ratio. This will look fine when you export 4:3 also, but as you can see, it's getting cropped once you set the dimensions to 16:9, as they are positioned too high on the screen. The only options are to record the video with the text positioned for a 16:9 screen, or to disable the text overlay when exporting.
