Cards on the table vs in your hand

[anthooony]

I actually have a question for this topic:

One-shot items are potions and other spells, but if they are not in your hand, does that mean you can still use them during a combat? In the Rules, it states "You may NOT change your used and carried items during a combat or while running away."

Does that mean that I can only play Monsters/One-Shot Items/etc that are in my hand and not "carried" (turned sideways/not in my hand) during combat?

Hope my question makes sense. Sorry in advanced.