FCPX cross dissolve transition duration..cannot change

Hi,
I am using FCPX 10.0.5 version purchased a week ago and I am learning to use it. One of the things that I am struggling with here is, the basic cross dissolve transition that I have between my video clips cannot be changed in duration. It did once, not it is stuck and no matter how many times I am trying to change the duration of it, it just doesn't change. the first time, after I included the cross dissolve transition, I was able to change the duration, but after that, I am trying to increase it to a higher number of seconds, and it just does not change.

Any help?

thanks
Einstein

Thanks for the response. Is there an alternative to "cross dissolve" transition, that I can include between two clips, whose duration can be set at will and is not dependent on the available media or the clip length?

thanks
Einstein