I double click the transition. The transition "dialog" opens in the upper right frame of the application. There is a little box with the transition time. I update the transition time and hit enter, and it reverts to 1.0 seconds. I try again but this time I use the "Apply to all transitions" button and the same thing happens, the transition time reverts to 1.0. It does not matter what value I enter into the dialog.
To lengthen a transition try the following:
1. Click to select the Transition
2. Look at the top meny bar to find the Transition name and duration.
3. Select the duration and enter the length you would like the transaction to be.
4. HIT ENTER ON YOUR KEYBOARD.
Failing to hit the enter key means that the transition duration change does not stick.
It is exactly what I do: hitting the enter key on the keyboard.
But this is not solving the problem of the transition time every time coming reseting to 1.0 s
I don't know why but this bug is coming times to times for transitions, not every time. But when it comes for a given transition, no way to solve it, even by changing transition type !
I agree with arinha, too much bugs in this version of iMovie !!
For example, another bug I found:
When I work in the timeline with the option Presentation / time line adjustement and right click on a transition to adjust (display precision edit) (sorry my iMovie is in french language so I don't know the exact english commands), when I want to exit the precision editor, iMovie freezes and consequently also Mavericks. No way to continue, even after waiting 30 minutes (I did the trial) ! Then the only choice I have is to reboot the iMac and restart the job.
When I work in the timeline without the option Presentation / time line adjustement I don't have this bug.
==> AMAZING !
Please Apple, can you solve quickly all those bugs and continue, as done in the past, to deliver great apps and not doing like the others: apps with bugs...