I am making a short movie set to music and I want to make clips longer so that they're not too fast and when I lengthen one from 20 frames to 2 seconds and 12 frames, it shortens pervious clips down to 1 frame and it is really annoying because I've got everything set to music so that the lyrics fit with the image and now they're all out of sync. How do I stop it doing this?!?!?!?!?!?!?!?