It sounds like you've accidentally turned Track Changes on. When you press
Ctrl+Shift+E, you should see TRK toggle on/off in the status bar (bottom of
the Word window... or Track Changes: On/Off if it's Word 2007 and if that
indicator is enabled in the status bar [right-click the status bar and check
Track Changes if you don't see it in the status bar]). Use Ctrl+Shift+E to
toggle track changes OFF, then use one of the methods below to accept what
you've already typed to remove tracked changes.
If this is Word 2003 or earlier, used the Reviewing toolbar, and click the
dropdown arrow next to the Accept tool, then choose Accept All Changes in
Document (look for the checkmark tool).
If this is Word 2007, click the dropdown arrow just below Accept in the
Review ribbon tab, then click Accept All Changes...