Bezier Handles Missing in graph editor

When you are editing the speed graph you cannot change speed without moving the speed indicator up or down. You change the time the speed changes happen by dragging the control handle left or right. If you Keep the speed at the same level, say 15 pixels per second, and you drag a handle all the way left or right you will not change the timing of anything, but if you drag the speed handle up or down and move the control handle right or left you can change when the speed change happens.

It takes a bit of time to figure out the graph editor. It is very well suited to some tasks and very poorly suited to others. Manipulating a motion path in 2D or 3D space is extremely difficult when you separate dimensions and try to do it in the graph editor. It is very easy to do accurately if you use the pen tool in the comp panel. Changing acceleration and deceleration of an animation is very easy to do and visualize using the speed graph. These are two completely different operations.

If you want to edit the speed graph after you have separated dimensions when you start you will have to individually select the position properties to be able to grab the handles because all speed indicators will be in the same spot.

One other thing to be aware of, if you separate values you will lose the ability to manipulate the bezier control handles in the Composition panel making it much more difficult to precisely adjust the motion path. More than 99% of the time I do not separate dimensions and more than 99% of the time I adjust the incoming and outgoing speed of position animations by consulting and if necessary, editing the speed graph. On the rare occasion that I do separate dimensions it is because I have to match the timing of some other part of the animation that requires x to start moving at a different time than y. That is a rare problem that cannot be solved by keeping the dimensions together and setting an extra keyframe.