Installing a new theme does not prove anything, it remains a template code change implementation issue. So the best would be if you finish the implementation on one before you go for the next.
I cannot provide with more help without seeing some code, but trust me, there is nothing difficult here.
Some parts i didn't find in my theme.....i don't know exactly where....i will try to install again the code changes. I will put here the code i didn't find in my theme...
The main part when implementing our mods template code change on a custom style is to determine from which one of the two default ones yours is the closest. Usually, if you cannot find any forum_fn.js file in your template/ directory, it means that the theme is based on subsilver2. Use prosilver ones to start with if you have this file.