I'm pretty new to AE so I will probably loose myself trying to explain my problem because I don't know all your terms.
I got this animation of a box extending its width. In order to accelerate it has key-frames. I learned how to extend the key-frames proportionally but the problem is the width. If I enter the width of the last key-frame only, the width to the other key-frames is the same as before. So instead of getting the same animation but getting bigger width box through the whole sequence, I get the full width only from the pre-last and the last frame.