Dolores is programmed to be a sweet farmer's daughter, completely innocent to the world. Initially, Arnold had bigger aspirations for her, and near-succeeded in making her sentient, self-aware. Until Ford stepped in, and made sure she couldn't remember a thing until the reveries update.
While Dolores may now remember everything, that doesn't explain the apparent killing spree she is going on in the trailers. It made relative sense that she would open fire on all the board members, as they are the ones that are in control, but it doesn't explain why she would mercilessly kill humans as portrayed in the trailers.
Her chilling speech implies she has immensely changed from being the simple farmer's daughter, but why is she now a seemingly cold-blooded killer? Whatever her motivations, we know Arnold had hopes for her to be who she is now. Hopefully Season 2 will provide more backstory on their relationship to give us a better idea.
Have any other questions for Season 2 of Westworld? Be sure to comment below!