images not scaling for different devices on simulator

I have been developing an app and the simulator I’ve been using  is the default “iphone”. I’ve been developing this for a week then I decided to try out the game on a different device and everything is all screwed up. The images aren’t the same size and they arent in the same position as they were on the original simulator. Also, I had an algorithm so that whenever a the size of a ball in my game is decreased my 10%, the radius is decreased my 15, and the radius would always fit the ball perfectly. On a different simulator it does not fit. I don’t know how to fix the problem, if someone could help me it would be great.

What is in your config.lua file?  

http://coronalabs.com/blog/2012/12/04/the-ultimate-config-lua-file/

http://coronalabs.com/blog/2013/09/10/modernizing-the-config-lua/

What is in your config.lua file?  

http://coronalabs.com/blog/2012/12/04/the-ultimate-config-lua-file/

http://coronalabs.com/blog/2013/09/10/modernizing-the-config-lua/