I am adding a special effect using the bezier mask, and while I can create the mask defined by points in various locations, when I move forward a few frames and move the mask points to their location in the new frame, the mask points also move on the original frame. I don't want them to do that. I want the original frame to have the original mask, and the new frame to have the new mask point locations, and so on (creating an effect in a stop motion movie). This is not motion tracking, but moving the location and shape of the mask from frame to frame. After updating the mask on several future frames, I find that the updated mask shape and position changes carried through to all the previous frames too, ruining the work I did in each of those frames. How can I accomplish this? I've seen no videos online to explain what I need to do in Vegas Pro 18. I did see one where a person did this exact thing in Adobe After Effects, and I have to believe it is possible to do it in Vegas Pro, but I can't figure out how.