Object resolution

Hi guys, I am making a 2d videogame for android but I have a several issue; there are a lot of different devices for android and so I don't know how to make a script that allow to autoresize objects. I know that there isn't a true method. I tried a lot of things but now I don't know how to do what I want. Also I have a problem with game simulation; I can set different resolutions (unity already has from 480x320 to 1280x80) but for example if I add another one (1920x1080) unity doesn't show me the 1920x1080 because the window dedicated for simulations isn't so big.

Waiting for help.