In order to get history of a code snippet, click on the name of that code snippet and then click on History.

This will show all of the versions of the selected code snippet in a popup presented below.

Tip

Code Snippet 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.