Unwanted highlighting and locking text - leave my input alone!

Using Firefox during recent times drives me absolutely insane! It is one massive failed "automated second guess attempt". I try to go back to correct a word and the text turns blue, I can't space it out, backspace it out or delete-key it out. When going back in a paragraph to enter a word I missed, I often have to click over and over and over, fiddling repeated with the cursor movement keys, the backspace and delete key to force the cursor back to where I want to enter or change text. The automated editor feature or whatever it is you call it, has cost me much more time than you are attempting to save me. In fact, I can never think of a time where your "helpful editor" ever actually took an action (like highlighting a word or paragraph), that was ever my intention. I am almost at the point of hanging up trying to use your browser and as much as I dislike Microsoft and Google, it looks like IE or Chrome is my only option. Is there any way to turn this massive personal invasion editor function off?