Change your resolution to 1024 x 768 and see if DosBox loads differently.
Im not sure if its like notepad where the last place you close it is the first place it loads back up to, but maybe adjust it, exit the long way (exit option in game, exit command in prompt) then maybe *fingers and toes crossed* it'll move next time you open it again.
Im sure an expert will have more orthodox ways for you to try
