C:\Users\<Your Windows Logon Name>\AppData\Roaming\OBD_Games\OBDWW1 Over Flanders Fields
Also make sure you do not resave as a ".txt" file. If you use notepad, when saving, you need to change the file type to *.* - then save as ViewUI.xml.
For me it always helps to enable the viewing of file extensions in Windows explorer, then you can see what is happening.