help with screens?

normally im able to just double click the top of my screens and then will fall down to the dock.. but im not able to

i have to hit the yellow circle for them to drop down now.. is there a setting?

I think you mean "windows," not "screens."

There's a checkbox in the Appearance pane of System Preferences. "Minimize when double-clicking a window title bar." You want to make sure it's checked.