you cant use letters you have already used before to try to find out if other letters don't work which really limits you making it more annoying that enjoyable 

You can still use the grayed out letters! I know the color makes them look a bit like they are disabled, but they are not.

no tryed and made word that where even shown in the preview as working and if they where grayed out or if the letters where not in the green space if i had some green it would not lt me use the words

That does not sound right. Can you post a screenshot or a video of the problem?