@Paul Lalancette
If you are using TurboTax Online, you can switch to French by signing in through this link: https://ww1.2022.turbotaxonline.intuit.ca/signout?_swlg=fr
If you are using TurboTax CD/Download, you must reinstall your software using the French version, which you can find here: https://turboimpot.intuit.ca/impot/logiciels/installation/
You can use the same Licence Code that you used to install the English version.