Hi @sofiechil,
This is intended behavior – if you click exactly on the arrow as you see the icon is changed and it’s expanded this means the menu will not be closed automatically even if you hover out of it. If you click exactly on the arrow again – it’s collapsed and un-hovering the section closes it.
You don’t need to click exactly on the arrow to open the menu – to open menu you click on the word and the behavior described above happens only if you click exactly on the arrow – that’s the meaning of it.
I hope that helps!