Hei! I have been frustrated about the fact that bookmarks management was way easier in previous versions of Opera, as far as I remember.

However, I found an extension that I hope can help those of you who want a simple solution.

Look here:

About the extension
Downloads 9,851
Category Productivity
Version 4.2
Size 9.8 KB
Last update Nov. 17, 2014
License Copyright 2014 escape75
https://addons.opera.com/en/extensions/details/bookmarks-import-export/?display=en

I JUST INSTALLED IT, AND IT WORKED JUST FINE.
SUPER-EASY TO USE

regards
from Norway!
OperaDigger1