The reason that the discussion topic you referred to was locked is because it deals with an old version of
Kunena that is no longer supported. For the current version of
Kunena there have been at least
four, separate discussion topics on this same subject:
... and these are just in the last two weeks! :ohmy:
We do appreciate the questions that people ask but we would appreciate your help in being a bit more thorough in searching for the information, please.
There is no single answer that addresses the individual peculiarities of the thousands of Joomla site templates in use all over the world. Lacking specific details, the answer to your question is contained in the topics I have referred to above (and in many more like them) and, in all cases. the answer is the same: please read the Wiki article
Changing Template and its Colours - the Basics
.
I hope this information helps. In the absence of any other information, that's all I can do for you at this time.