Upgrade Wizard - Bad permissions on files

I’ve just completed my installation of SuiteCRM 7.12.
However, I still have some points to make in order to go further…
When I run the Upgrade Wizard, I encounter issues with step 1. Some files (a lot of to be frank) has bad permissions: Menu.php, controller.php, en_us.lang.php…
At first sight all these files are all in the directory “modules”. Their permissions are 0775. Could you please tell me what should be their permission to not have any more error messages when running the system check?
Thanks in advance for your help.