I've tried morphing them into a happy daydream but then a new, different element comes into play which makes the previous day mare worse. I want to quit daydreaming all together.
Personally, when I catch myself in a negative daydream, I visualize smashing it with a hammer as if it's playing on an old T.V. and then remind myself that it isn't real. Try to do that and then turn the daydream around to make it positive or picture yourself saving the situation.
I like the idea of smashing it with a hammer. I want to try and resolve the issue by doing something productive in real life. Every time I resolve the issue in the daydream, I find my dream self facing a harder predictament than before.