1- Go into the folder where you have installed YRR;
2- Search the file called ra2md.ini;
3- Open it whit Notepad (or a similar program);
4- Serch the video part of the file, and find these two command line:
ScreenWidth=1600
ScreenHeight=900
5-Now change the parameters: insted of 1600 write your width of your screen, and do the same work whit the height. For exemple if your screen resolution is 1024x768 the code must be:
ScreenWidth=1024
ScreenHeight=768