fading audio in/out

am using imovie 5.0.2. i used to have an audio "line" that i could use to fade audio in & out and eliminate completely. the line is no longer there. i have the option to check boxes to the right of the timeline that results in eliminating (lowering) all audio in a specified timeline (2 audio tracks and audio that has not been extracted from video clips). i can also use a "slide" tool that allows me to lower or raise audio from 0% to 100%. please advise; where is that audio "line" ?