Your answer did work, once I figured out to tap on the folder first to bring it to the forefront and then hold down on the bookmark and drag it. Thank you.
Go to the main Settings app on your phone, look perhaps in the Display section for an option called "Auto-rotate screen" or similar and enable it. You may also find this option exploring the quick settings toggles in the notifications area.
Then it'll work as expected.
It might be disabled, because weirdly it seems Opera auto-rotates videos regardless of this setting.
Something that's missing in Opera albeit present in any other Android app is the tooltip that appears when you long-press buttons, perhaps it'd make using the menu easier if this could be implemented there.
Not just any beta version, it has to be 12.00 beta specifically.
Here you go, with lot of additional info (which you should read, especially the caveats). And do bear in mind that it is old (2012), and also an alpha/beta dev build, or you could even call it an experiment.
You only have 1GByte RAM on your S2.In reality you even have less. Your video gpu takes memory away too. You need a device with at least 3 gigabyte on HD 1920x1080 and 2 gigabyte on HD 720p screen resolution devices.
I have a 1 GB RAM 540x960 resolution device, I think Opera 12 (Classic) handled more than 10 pages without having to reload them. So, this is not a valid excuse, the new Opera can be improved.