Windows 10's dark mode changes the menus on the settings menu, File Explorer (in Insider builds) and a few other places, but it doesn't affect the vast majority of traditional apps people use. When you really, really want all of your programs to have light text and dark backgrounds in their menus, you can enable Windows' high-contrast mode.
Keep in mind, though, that high-contrast mode is a blunt instrument and makes a lot of things in UI look very ugly. For example, the live tiles in the Start menu look just awful. However, if you decide you want high-contrast mode, navigate to Settings-> Ease of Access -> High-Contrast and switch it to on.