Double click the file Fallout4Prefs.ini.To run Fallout 4 at a custom display resolution, do the following: How do I change the resolution in Fallout 4? Create a file with some global variables and some sections with scoped variables. Save and again make the ini file “Read Only”. The file is created upon very first start-up of the game. Initiation or ini files should be in the Docmuments/My Games/Fallout4 folder. You may be able to improve game performance by lowering or disabling some graphics settings in game, including the resolution. What do I do if Fallout 4 is running poorly on my PC? If you experience performance issues in game, you should reset your video options to what the Fallout 4 Launcher auto-detected. Fix 5: Stop CPU/memory hogging applications.Fix 2: Modify your video card settings.