I used to be able to change the theme colours.  Why can't I do that anymore?

Answer:

In version 1.18 I removed the theme colour options from the settings. 

I am trying to simplify the program right now so that I can upgrade it and hopefully introduce a version for the IPhone.  I have removed a few of the options to make it easier for me to convert it.  Once that is done, if I feel the need, I will reintroduce the options that I removed.