Quick Do It Yourself Fixes:
Shoe Adjustment: If you have taken out your window and didn't put window "arms" back into the "shoes" correctly, it could cause issues. Such as: window will not close all the way, or stay up when opened. Watch the video above to see how to fix this.
Picture on the left Shows the little metal arm on the window sash. Picture on the right shows the window "shoe" in the bottom of the window.