In this case you can create a shell script with the 'Screen Layout Editor'. Start ARandR from the 'Preferences' section of the menu. Apply all your screen settings. Then use 'Save As' from the 'Layout' menu. Navigate to your Desktop folder and enter a name. Click on the 'Open' button. A file will appear on your desktop. You can open this file with a text editor like leafpad.
Next time you boot up your system you can click on this file and execute it in order to restore your screen layout.