I don't know since when, but I believe from some update of El Capitan, this annoying sidebar preview on the right comes up everytime I open a new Finder window.
If I hide it using the mouse, it stays hidden in the current window but re-appears when I open a new window.
The sidebar on the left is all fine, showing items as it does normally.
Logically speaking, when I have switched to the preview window option and I already see items at the top, why would I need a second one at the right?
I couldn't find anything on the internet, people are just talking about how to hide sidebar preview in the Preview app. So any help would be greatly appreciated.
The image is attached: