Apparently whomever was responsible for populating the Status Bar was absent
the day it was assembled - the OverType Mode button is one that got left
out

It may have been intentional, however, because *very* few people use
it any more, but if you're one of those who do find it productive you can:
1- Use Word> Preferences> Edit & turn it on/off by way of a checkbox,
although that's a bit of a hassle if you use it frequently, so...
2- In the Customize Toolbars & Menus dialog you can add the command to a
toolbar from All Commands - Overtype, and/or
3- In that same dialog click the Keyboard button & assign a keyboard
shortcut to the Overtype command.
Quite honestly, I find it far more productive to select the content to be
replaced & just type the new stuff rather than having to remember when to
toggle back<->forth between Overtype & Insert
HTH |:>)
Bob Jones
[MVP] Office:Mac