How to use a different actor to run the game?

I dont know hot to use a different actor to run the game , i genarally can only use the default actor to run the game…

Hello! Every UE project has default GameMode, which can be selected in Project Settings. This GameMode class store Default Pawn class, that will be used that player’s actor. So, you can override this value in GameMode class. See for example Setting Up a Game Mode | Unreal Engine Documentation