I am not sure what I did, but a setting changed on my Ti-89 Titanium. I used to be able to go back to my input line and add new characters like a parenthesis or a missing number. This is one of the big advantages to a ti-89, however, somehow, When I go to insert new characters, they erase the current one infront of the input line. This is a big problem!!! How do I change it back!??