Unity scripted button text not locked to button

Sorry if there is an obvious answer to this question, but have locked the button to the center of the screen, but when I play with a resolution other than my monitors resolution, the button(s) moved around the screen while the clickable part of the button stays in the center. Here is my OnGUI script:

Code (JavaScript):

1.   function OnGUI(){
2.         if (GUI.Button(Rect(0, 20, 300, 30), "You are on level "+LevelSaveNumber)){
3.             if(LevelSaveNumber == 0){
4.                 Application.LoadLevel("Tutorial");
5.             }
6.            
7.             if(LevelSaveNumber == 2)
8.                 Application.LoadLevel("Tutorial");
9.     }
10.             if (GUI.Button(Rect(Screen.width - 200, 20 , 200, 30), "Delete Memory")){
11.                 PlayerPrefs.DeleteAll();
12.                 LevelSaveNumber = PlayerPrefs.GetInt("LevelSaveNumber");
13.         }
14.         if (GUI.Button(Rect(Screen.width/2-100, Screen.height/2 - 30,100, 30), "Exit")){
15.             Application.Quit();
16.         }
17. }
18. }

Thanks in advance for any help!

 

OnGUI is the legacy UI system, it was superseded by the canvas based system in 4.6+ (except for editor UI). If you are not particularly attached to what you have already it might be worth looking into the new system, it's far easier to configure and use: https://unity3d.com/learn/tutorials/topics/user-interface-ui

 

Yes, I did originally use this, but I had a problem getting the buttons to stay in there place on different sized screens, so I decided to go with OnGUI, but you see where that got me, but I probably just overlooked something as GUI has never really mattered to me before. Thanks!