How do I stop erasing words when typing in middle of sentance

[Guest]

I am writing a paper for school. When I started out I could go back to the
middle of a sentance and add another word or erase a word without altering
the rest of the text. Now when I try to add a word or correct a word, the
rest of the sentance is replaced with the new text. How do I get it to go
back to the way it was when I started?

 

[Guest]

Hit your insert key and you can stop it from replacing text as you type.

 

[Guest]

Thank you so much!! You really helped me out!!

Hit your insert key and you can stop it from replacing text as you type.