The auto-complete learns from what you previousosly typed in so you will have to type "doesn't" quite a few times to make it the dominante choice so it shows up, as for capitalising "i" you may need to start a brainstorm to get somebody to look into if an "i" is typed on its own it should be capitalised.

Another brainstorm should be cycling auto-complete, so if a word shows up in completion that you do not want, there should be a button assinghed to cylce through the possible words that that word could be.