I'm using Sony Vegas Pro 12. When I try animate text to make it appear word by word as I speak, I'm trying to use keyframes to do it and I have the text anchored to the left. When I added the rest of the words using keyframes, they appear as I want, but when I preview the whole thing, the whole string gets moved to the left and I have no idea what I'm doing wrong. When I move the mouse on the preview screen on the text, it somehow jumps on the correct position, but gets messed up when previewed again.
The reason for the text jumping around is that even though your text is anchored to the top left, the size of the text box is adjusting as you add more words. I have not found a way to adjust word by word in any of the vegas title editors (although I have seen the "typing" doogie howser effect using the Sony ProType Titler with some modifications).
Weird workaround is to type all of the text you want using the Titles and Text and then keyframe a mask to display the words in succession at your own pace using Pan/Crop. May actually be quicker this way, but here's how:
Create a rectangular mask around the words line by line, click the negative button below to invert the mask, then slide along to "reveal" them in sync with the timeline. Set your keyframes to HOLD (set the first one immediately and the rest will follow) so the words pop on instead of slide and your good to go!