Before talking with Apple on this subject I had made my changes in the little tempo window at the bottom of the screen...that's what changed the whole track. Now I am making the change in the Global Track window. I increased the tempo from 120 to 150 @ my split point but still I have the same tempo in all tracks from the speakers, except now in the tempo window at the bottom, the change shows the increase.
No wonder you were having problems. Changing the tempo in the transport at the bottom of the window does NOT put in a tempo change. It just changes the whole tempo globally. If you are changing it in the global tracks you should be fine.
But now, re-reading your original post with this new information, the problem was not really explained properly. In your original post you talked about splitting a file of a recorded click track, changing the tempo, and then the tempo of the click track changing. I thought you meant the tempo of that recorded click track changed. But now I am fairly sure you mean that Logic's metronome click tempo changed. Which is a completely different situation.
The tempo changes are working fine in the global track. The problem is that regular wav files do not follow tempo changes. Unless they are acid loops. They play back at a constant speed regardless of the tempo in Logic's transport. So now what I understand "the whole click track changes" to mean is that the metronome click is different and the recorded click track files are the same. Am I understanding the situation correctly now?
The solution is to convert the wav files to aif files and then use Flex editing to have them follow the tempo changes. Or else convert them to apple loops to follow the tempo.