I have just upgraded, for better or worse, from CC to 2014, and can now barely read the blue time code numbers, especially in the video effects of an individual clip. How can these be changed to yellow or white or some other color? Thank you.

That color change cannot be made at this time.
You can only change the overall brightness of the background.
I have had problems not seeing the little "tick" boxes for preference settings as they blended in with background.