Please be a bit patient with me, but when you say there is nothing to be found, are you saying you cannot find rgl_config.txt within your Documents folder? Are you sure you checked the correct path? There are two within Documents, one for the game and one for save games. If you copied the location I gave earlier
directly, it would
not have worked for you, you will need to change the username to whatever your PC username is. For example, the text highlighted
red would be different for you:
C:\Users\SerJon\Documents\Mount&Blade Warband
Let's do a test. Press the
Windows Key (
it looks like this on your keyboard) and
R at the same time. A small window will pop up called "Run". In here, type exactly this:
Documents/Mount&Blade Warband. The window should look like this after you have typed in it:
Now, hit ENTER. It should bring you directly to the correct path where
rgl_config.txt exists. Take a screenshot/picture of what you see in this new window and post it here for us.
Also, moving your brothers files to your PC probably won't solve anything.
EDIT
I included example pictures, just in case.