I have 3 users of the same role. If I save something on one of the users for instance in the cart then the other accounts can also see the things I added. How do I make it so that only the account that saves it can see what it did?
Then you made a serious mistake in your domain model. The shopping cart should by tied to a user. It seems that you have tied it to a role. This means that anybody with that role sees all what is in the cart.