Where is the FSX.cfg file in Windows 10 or 11?

On Windows 10 or 11, boxed Microsoft Flight Simulator X normally stores its configuration file at %APPDATA%\Microsoft\FSX\FSX.cfg. FSX: Steam Edition may instead use %APPDATA%\Microsoft\FSX-SE\FSX_SE.cfg, especially beside a boxed installation. Open %APPDATA%\Microsoft in File Explorer and check both folders if necessary. The active file is not normally in the FSX installation directory.

FSX.cfg locations for boxed and Steam Edition

The correct FSX.cfg location depends on the edition and the profile layout created when Steam Edition was first run.

Steam Edition commonly retains the original FSX folder and filename when installed on its own. If it detected boxed FSX, it can create the separate FSX-SE profile instead. Install history matters, so do not assume that every Steam installation uses the same path.

How do I open FSX.cfg when AppData is hidden?

Using the %APPDATA% shortcut opens the correct roaming profile without displaying hidden folders manually.

1. Close FSX before inspecting or editing its configuration.
2. Press Windows key + R to open the Run box.
3. Enter %APPDATA%\Microsoft and press Enter.
4. Open FSX or FSX-SE, depending on which folder exists.
5. Enable file extensions from File Explorer's View options. Look for FSX.cfg or FSX_SE.cfg.

%APPDATA% normally expands to C:\Users\your-name\AppData\Roaming. Windows may display the file simply as FSX when known extensions are hidden.

Which FSX configuration file is active?

The active file is the one whose modification time changes after the relevant FSX edition saves a setting.

1. Close boxed FSX and Steam Edition.
2. Note the modification times of any FSX.cfg and FSX_SE.cfg files.
3. Start the edition you use, change a harmless setting, apply it and exit normally.
4. Refresh both folders and check which file has the new modification time.

A mistake we see often is editing an old FSX.cfg left by boxed FSX while Steam Edition is reading FSX_SE.cfg. Also avoid files copied into backup folders: their names may match, but FSX will not read them there.

What if FSX.cfg is missing?

FSX creates its configuration file when it establishes a user profile, so launch the simulator, let it reach its main screen and close it normally.

• Check both FSX and FSX-SE under %APPDATA%\Microsoft.
• Make sure you are viewing AppData for the Windows account that actually runs FSX.
• If you supplied credentials for another account when launching as administrator, that account may have a separate AppData profile.
• Turn on filename extensions so that FSX.cfg is not mistaken for an extensionless file.

If FSX crashes before creating or saving the file, follow our Windows 10 and 11 startup troubleshooting steps rather than creating a blank configuration file manually.

Can I edit or reset FSX.cfg safely?

Yes, provided FSX is closed and the original file is backed up first.

1. Back up the file by copying it somewhere safe or renaming it to FSX.cfg.bak or FSX_SE.cfg.bak. Our guide to backing up FSX settings and add-on files identifies the other folders worth preserving.
2. Edit with a plain-text editor such as Notepad. Preserve section headings and save the file with its original .cfg extension, not .cfg.txt.
3. Reset when troubleshooting by leaving the renamed backup in place and launching FSX. The simulator will generate a fresh configuration with default settings.
4. Test before restoring tweaks. Installed aircraft and scenery are not removed, but manual configuration lines, graphics settings and some add-on trust records may need to be added again.

Do not replace the whole file with a generic configuration downloaded for another computer. Hardware entries and add-on lines may not match your installation. If memory exhaustion is the reason for editing it, use our FSX out-of-memory diagnosis and safe configuration changes rather than applying unrelated tweaks.