That's the complaint I have against the browser. I got so frustrated with it I uninstalled it and went to Safari instead. It's a bit hinky but I can handle it.
I just noticed that there is an Opera shortcut on my desktop labeled “Bookmarks.” I clicked on it and it opens a page with all of my old IE bookmarks on a web page sorted by folder. I can search the page and find the bookmarks. Not exactly convenient but not entirely useless. I will give Safari a try too.
Opera:
Up at top left toolbar...
File > Import/Export... it’s all there.
Right side, drop-down search engines... Manage Search Engines, specify what you want.