@leocg it is under settings/ security and privacy / site settings and then permissions.
But the problem doesn't seem to be there anymore. So the issue seems to be solved and may come from the site itself ...
Thanks for your support anyway and good day or night.
Pierre

I can't open one of the private websites I use regularly (for association work) and would like to add it to the trusted site list. How can I do so. I see the list but can't add anything to it.