It is difficult to even search for this as its not the title bar
That's called a menu bar and it's usually not customizable unless a program supports themes that allow you to change it.
There's 2 types of menu bars. The normal Windows drawn one, and another type called "owner drawn". The owner drawn menus allow the programmer to draw every piece of the menu bar (including choosing any and all colors).
I recently wrote a program that uses an owner drawn menu myself. I was a bit lazy and only colored the menu items white. I left the rest of the bar gray. Look closely and you'll see the difference.
So what you need to look for is a way to change the default menu bar color in Windows. Of course programmers can over-ride that if they are using owner drawn menus.
Try a Google search for "change default menu bar color" and maybe you'll get somewhere, maybe not. I found one thread and it required the user to create a customized Windows theme using 3rd party software (which is known to cause Windows issues). I recommend avoiding that route, it could end bad. Maybe a custom theme would be OK, but avoid the 3rd party software.