Thanks to everyone for your help.
I understand that we are going on technical operations that would be better not done for a non-expert person like me.
I have decided that I keep the old version of Calibre which has the ideal font and size for my tastes and my needs.
Thanks again for your help and patience with me
I forgot ... yesterday I was trying the latest version in an attempt to find an alternative font. Well, even using SMALL sizes, the search result window always forces me to scroll to see the cover. So, in my opinion, there are some problems in the new version of Calibre. For this I will return to use the old one but I hope that in the future these problems can be solved. Ciao