How do you swap equipped items ?
When you put items you want to use into your inventory slots, the slots are numbered.
Pressing a number on your keyboard will unequip the item you have equipped currently, and equip the item in the inventory slot whose number you just pressed.
(Note: I’m assuming you’re playing with mouse & keyboard. This should still work on a console; I’m just not sure how to activate a numbered inventory slot with a controller.)