On a video track it says X-pos Y-pos Width Height. Can I access the curves behind them? Under MEP14 and earlier I could. On MEP 15,16,17 it's a tease, I can't make the curves show on the track. But those words on the track imply that there is something there.
Select your clip and got to 'Effects' tab >> 'Movement effects' and pick 'Size/Position' and you should get a window where you can very easily edit your curves. To make the curves visible you need to click on the little 'eye' icons for each individual effect shown here (VPX screen shot).
Note also the double down arrows half visible at the bottom left. If they are pointing up (eg 2X ^) this section won't be seen -- just click on them to restore. The new system may take some getting used to but is way way easier!