UI elements problem

Hi there. I have a problem with ui. I have a menu composed from ui elements. I built and run that app on my Samsung Galaxy S3. Everything went normal, but when i tryied the same app on another smartphone(with another resolution), the ui elements went outside of the screen( or at least change their position). I want ya'll to know that i've already looked through similar question, but nothing helped me out. I have the following code:

 void OnGUI()
     {
         float rx = Screen.width / 1080.0f;
         float ry = Screen.height / 1920.0f;
         Matrix4x4.TRS(new Vector3(0,0,0),Quaternion.identity,new Vector3(rx,ry,1));
     
         GUI.skin = GameSkin;
     
         if (GUI.Button (ResizeGUI (GenerateRect), "GENERATE"))
                         GenerateNumbers ();
         }
     
     Rect ResizeGUI(Rect _rect)
     {
         float FilScreenWidth = _rect.width / 1080;
         float rectWidth = FilScreenWidth * Screen.width;
         float FilScreenHeight = _rect.height / 1920;
         float rectHeight = FilScreenHeight * Screen.height;
         float rectX = (_rect.x / 1080) * Screen.width;
         float rectY = (_rect.y / 1920) * Screen.height;
         return new Rect(rectX,rectY,rectWidth,rectHeight);
     }
 

P.S. Sorry for bad english