Need to access SQL using “mysql root -p”

Hey guys: I have one question access mysql using command line. I have no problem to access mysql based on this commend line “mysql –host=localhost –user=root –password=”mypassword””; however, I have issue access mysql using the conventional way: “mysql root -p”. I’ve tried many times to change root password. But I still only can access mysql using this commend line “mysql –host=localhost –user=root –password=”mypassword””. Any comments are welcoming!