In Word, click on Tools | Options | Edit | check the "Typing
replaces selection" box | OK.

SK wrote:

I used to be able to highlight a word in a document and begin to type
something different, and it would automatically replace the highlighted text
with the new text. It's not the Overwrite function, it was something
different.

Now, all of the sudden, I will highlight a word and start to type in new
text, but it places the new text next to the old text, instead of replacing
it.

Any idea why?? Any idea how to fix??

Thank you!