Final Cut Pro - The Secrets of the Right-Pointing Arrow
Its almost impossible to see... and equally impossible to live without.
Its not like its obvious or anything, but a great deal of the look of the Timeline is controlled from a itty-bitty, teeny-tiny, right-pointing arrow at the bottom of the Timeline.
Just to the right of the four column track height button.
Click the arrow and look at all the different choices you have. Each of these is a toggle. Select, or deselect, each one and watch what happens.