Thank you Alex and Stefan for your answers.
You are right about the versions. We are way too much behind in terms of security (and probably features)… However we have had some slight modifications done to the software and I am not really able to update the system and everything so it makes a complicated old way to do it…
Here is where we would like to add a choice of countries (the default one would be great):
It is in any event we create in the calendar. Either in the main part or in the personalized part
Since we do not really need all the countries, I have made work around by using the Select box and in case there is a new one, I can still add manually another entry.
I will try to update our configuration, but this may take a lot of time for me. Thank you for the links for the way to do it.
Cheers and thank you for the very good work,