Here is a video tutorial on Automation and everything you want to know about.
As always video is video, manual sucks.
This is a good example of why we don't encourage referencing videos. Often the copy isn't written well enough and can leave the viewer with the wrong impression. Youtube videos don't have to go through the rigors of either editorial or peer review.
For example, the narrator in that vid, referring to Touch mode, makes the statement, "Every time I let go, it snaps back to unity gain."
This is an incorrect statement, by itself.
Then he goes on to discuss Latch mode and states, ". . and then continues to record automation even after I let the fader go."
Also incorrect. No new data is "recorded" after you let the fader go.
For Write mode, his opening statement says, ". . . will record one solid position without changing it whatsoever."
Also not true. You're free to change the position in Write mode.
Someone who is trying to learn exactly how these functions operate, without having any prior knowledge of them, could be seriously misled by that video.