In order to get history of a locator, click on the key of that locator and then click on History icon 
This will show all of the versions of the selected locator in a popup presented below.
Tip
Locator creation/update time uses the users' local time
In order to see the delta between the selected version and the current version, just click on the revision date for that version. Once clicked, the following page appears and the delta between that version and the current version is highlighted in blue as follows with the current version shown on the left. You can individually select each modification and hit apply to revert a specific change back to an older version.
