If your CSV files are often not opening properly, the reason is that regional settings in windows use commas as the default decimal point character (instead of a period in english countries), and so the default separator is a semi-colon. In order for them to open CSV's without having to import it every time, they can change those regional settings:
- In the start bar, search "Control Panel" (Panneau de Configuration)
- Go to the Region Settings
- Go to the Region - Dates, Numbers, etc... settings
- Click Additional Settings (Parametres Supplementaires)
- Change the Caractere Decimal to a period, and the separateur de listes, to a comma.
- Click Apply (Appliquer), then close.
- Close all excel windows and try to reopen the file.