I'm not sure of Opera 22 Next, so am speaking from the context of Opera 21 (the last stable version of Opera) which I use. If it works for you, then super.
Of course you can do control D (if you can remember it 🙂 but there are other ways also, that it's quite good to know, and which are easier to remember.
First, I'm not aware of a way to change the extension icons on the toolbar. On adding bookmarks, it's no problem in Opera 21.
You can also drag the icon from the page you are on (all the way to the left of the address bar) to the bookmarks bar. Or drag the thumbnail of a site you saved to the Speed dial to the bookmarks bar. And a very good Opera extension is: Add Bookmark. https://addons.opera.com/en/extensions/details/add-bookmark/?display=en
It will give you a star in the address bar (right side). (It's also supposed to give you a star in the context menu when you right click on an empty space on a web page (but that's being worked on for an update) (Still the star in the address bar is useful. I use this extension all the time. When you make a bookmark with the extension, "Add Bookmark," it lets you rather seamlessly immediately select the folder you want to put it in. (Making a bookmark with Control D doesn't do that). And the dragging from the address bar icon or the speed dial takes a drop more time). So "Add Bookmark" is good.
Hope this helps. There's enough through these alternative methods to easily make the bookmarks you need (at least in Opera 21 :). When you're using Next, you're on the new frontier, taking (smile) chances . . .
I find a good bookmarks manager is Neater Bookmarks (it's a Chrome extension). https://chrome.google.com/webstore/detail/neater-bookmarks/ofgjggbjanlhbgaemjbkiegeebmccifi?hl=en-US
To download a Chrome Extension, you need to first download the Opera extension, called, "Download Chrome Extension." https://addons.opera.com/en/extensions/details/download-chrome-extension-9/?display=en