You can right click on it to set home. But the save home button saves the position of the sled wherever it is as home.
edit: the right click context menu from the webcontrol work area display shows a “define home” command button to set the home position:
pressing return to center will allow the sled to go back to the original home and then you can press the save home button:
and then the GO HOME button will move the sled back to the center until it is defined again:
Webcontrol tells the controller to save its home position, so you can power cycle once it is set and it will persist.