The answers are in the details.
What version of Premiere Elements are you using and on what computer operating system?
If it is not already, set Cross Dissolve video transition as the default transition.
Then, select/highlight all the clips to which you want Cross Dissolve applied.
Then go to Timeline menu, click on Apply Default Transition.
You could also select all the clip, right click anywhere in the highlight, and, in the pop up menu, select Apply Default Transition.
Please let us know if that works for you. If not, please supply more details so that we can be more specific in feature locations.
I am using PE11 with windows 7.
Instead of clicking on "apply default transition" I was cliking on "apply default transition along CTI"
What you said works. Thanks.
Great news. Glad that worked for you.