Some legacy versions (FluidSIM 3 and early 4) store the language in the Windows Registry.
Steps:
| Problem | Likely Cause | Solution | | :--- | :--- | :--- | | "Options" menu is greyed out | You opened a student assessment file (.fsa) | Open a blank circuit or standard .fsproj file first. | | Added /L EN but still German | English DLL files missing | Re-run installer and add "English language support" under Modify. | | Only Chinese and English show | You have the Simplified Chinese edition | You cannot add German/French. You must buy the EU edition. | | FluidSIM crashes after language change | Corrupted user preferences | Delete the FluidSIM.ini file in %AppData%\Festo Didactic\ |