Help required with JBOD setup

A long time ago I turned off the raid function and swopped to JBOD. Now I cannot remember how you can “see” what is on each drive and how to select which of the two hdd to save new stuff to?
I cannot see anything in the online manual for the life of me.

I also find that in the last 2 years nothing seems to have improved with the slow interface when you login in with the 192. address.
I found it with win 7 and now with win10,that the dashboard and allied pages are very very slow to respond to inputs or commands.
I am getting green lights on every thing, using a switch, with cat 6 cables, and have the latest updates on everything, but the dashboard is very slow to respond to inputs or hangs and gives a long running scrip error.
I am on version 2.31.183 and removed Plex from the apps as this completely slowed down every thing, but some thing else is wrong as I see on several YouTube videos where as the mouse is used to navigate the dashboard and the on screen response is immediate…
Any suggestions what to look at please?