Switching on Track Changes

The quickest way to start tracking the changes is to double click on the TRK button in the status bar
SS
Alternatively you can select (Tools > Track Changes) or use the shortcut key (Ctrl + Shift + E).
You can also activate track changes from the Track Changes button on the Reviewing toolbar.

2010 and 2007 - click on "track changes off" indicator on the status bar (also has display options)
Review tab, Track Changes, button indicators

2003 - click on TRK on the status bar
Is there any indication on Tools > Track Changes ??