There are two aspects to Home Pages. There's the creation of a Home Page; which you then customize to fit the role; and the second part which is to properly assign the correct Home Page to each Role, which you do in the Manage Roles area.
First make sure that the Home Page for Role B is setup the way that you want (start in Home < Settings < Pages < Role B Home Page). Once you have done that you then need to go over to your USERS icon, then click on the link (top right) Manage Roles. For Role B, make sure on the User Interface tab, that you have chosen the Role B Home Page in the drop down.
Then re-test. If testing is an issue; try creating a separate User that you can login on a different browser with so you can be logged in both as the Administrator and as another Role under a different user-login. This way you can simply "fix" things; and then refresh the other browser to see the changes without having to switch roles constantly in the Test as a Role/Test as a User feature.