I have the exact same problem here Xay. I am running Windows 7; cannot set my screen resolution any higher; cannot see start/menu button to change to fullscreen as suggested or hide Task Bar which might help. I cannot see any configuration folder to make change in there.
I agree with other comments, we have waited a long time for this game to come out and now it is unplayable like this. Bitterly disappointed.
Surely it is easier for Arthur to change the config settings so it starts in full screen like all the other games and put that out as an update.
As it stands, if I can't get this resolved, I will not be buying this one. I can't believe I would actually miss a game. I have the full set!!!!