If, like me, you use a game-pad to play this game you may have difficulty selecting the correct Item. The trouble is that whether you use the D-pad or A, B, X, and Y buttons (or whatever the buttons are on your controller), they are usually arranged in a diamond formation. Ideally there should be an option to change the formation of the quickslots on the HUD to correspond with the button layout on the controller: that is up, down, left and right; or North, South, East and West.
While I agree, I found it much handier to use A, B, LB and RB on my X-box pad. They're pretty easy and accessible that way.