Just wondering how to fix this problem.

When I am typing on regular Wordperfect 9 and I would like to go back a couple of lines to backspace a word and retype something else the word that aI type writes over top of the word proceding where I am typing. its very annoying. and by this happening I cannot change anything that I have typed unless I retype everything that Comes after the word or line I am fixing.

If anyone can understand what I am saying please help.
I know it's a setting Somewhere but I cannot remember where it is
Thanks all.