This is no doubt really simple but I don't see it ... In DOpus when I clicked the "display this folder in the other file display" button, it now shows two displays top & bottom. It used to be left and right. How can I get it back to the original setting?
You probably see this small icon in the lister's header, the = symbol at the right hand side:
Alternatively, you can use following command (you can just type or paste it into the command line):
Set DUAL TOGGLELAYOUT
I don't see the header mentioned ... however, I stumbled across Lister options at the top that had "Dual Horizontal", "Dual Vertical" and a couple of others. Clicking "Dual Vertical" did the trick.
I should have mentioned where to find that option, sorry. Maybe you want to have it in the display border. You can find it in -> Settings -> File Displays -> Border -> Enable horizontal/vertical layout button, amongst other functions, like the swap button, etc.