Insert/Overwrite Key

I dictated a bunch of text, and now I have bunches of lower case letters I need to make upper case. Should be a simple fix to place the cursor in front of the offending letter, turn off the "insert" key and type a capitalized letter on top of it... except I can't find a way to turn off the "insert" function so I have to delete and then retype.

I saw in another thread that there was a solution for people who have the long keyboards with the keypads, but I have the short wireless keyboard - no keypad. Help?