There is Early Access (EA) and Early Access Experimental. By default you play Early Access. If you want to play Experimental, you have to install it separately with the EPIC Launcher. It should be available in your EPIC Library as an extra game.
Try not to mix the savegames. Savegames from Experimental are incompatible with EA, so be sure to keep a savegame from EA just for the case you need to switch back.