Screen Wallpaper Problem topic

Well , everytime when i press the home - middle button my wallpaper gets really big and i have to set it again everytime, it`s pretty annyoing.That problem accured when i tried the ''Easy start'' and i didn`t like it then i switch to the normal Xperia Home . Restarting doesn`t fix it. My model is D2303.
How can i fix it ?