@cris2d2 Oh I misunderstood! I didn't realize you were going from opera to opera. Here's what I did in the past for extensions.
If you navigate to the right folder, for me:
it was something like C:/users/mellofellow/appdata/local/...
but you can look it up in Opera:about or using the menus
Find the extensions folder and you'll see a bunch of subfolders with long letter names like: jckjxzckjxznckjlxznccc
each of those is for a different extension and most are readable using JSON readers (I use sublime text).
So, once I have reinstalled the extensions, it is just a matter of reading through the new folders to see which extension is which, then manually writing over the settings with the old ones (again use sublime text).
This worked for me but really isn't worth it unless you have a few extensions with a lot of settings. It is so much faster to just put in the settings anew.
For the opera settings, one workaround may be to do the same via cut and paste. Or you could try going to about:config or opera:config taking screen shots and just updating the new install?
It's a shame, opera was the leader in innovation with tabbed browsing etc. but has since become bloated an removed features unecessarily. After switching to FF, with the same set of tabs open, i went from +4GB Ram usage and hourly freezes to 1GB, fluid browsing.