add to bookmark default location in opera is at the first of the menu of bookmarks and not at the end of the menu of bookmarks like other browsers that I used before.
So is there are any way to change that behavior?
No, there isn't. And opera is poor/problematic in general when it comes to bookmark management
I added this extension https://addons.opera.com/en/extensions/details/add-bookmark/
so if I want to add bookmark at the end of bookmarks I use it, and if I want otherwise I use the default bookmark button.