if you mean, modify colors for one of predefined skins, then you must do it using Custom CSS. You need to use for examples Firebug for Firefox (this tool was described in doc included into theme or also you can have a look on http://themes.muffingroup.com/betheme/documentation/#theme-customizations) and each custom css should be used in Theme options > Layout > Custom CSS section. But of course you should have some css skills.
We do not recommend to modify core theme files, because after update this will back to default version and all your changes will gone.
But where you changed them? Directly in file? Because we do not recommend modify any core theme files. Especially for css changes, we created Custom CSS section. Please also check if you don`t have turned on Static CSS in Theme options > Getting stared > General section because this should be turned off.
Comments
if you mean, modify colors for one of predefined skins, then you must do it using Custom CSS. You need to use for examples Firebug for Firefox (this tool was described in doc included into theme or also you can have a look on http://themes.muffingroup.com/betheme/documentation/#theme-customizations) and each custom css should be used in Theme options > Layout > Custom CSS section. But of course you should have some css skills.
We do not recommend to modify core theme files, because after update this will back to default version and all your changes will gone.
Thanks for understanding!