It is possible to change the users on your account, there are a couple of ways to do this: -
1. To change the named users
To do this, simply got to My Account > User Administration (Only master users can do this) and then select to Edit the Details for the users.
This will allow you to change the details of the users
2. To change the access the user has
To change the access for the user, simply go to My Account > User Administration (Only master users can do this) and then select to Edit the Details for the user.
Within that section you can bring up and select which accesses/modules people have access to
3. To change the packages people are on
Mix and match is only allowed with one user on the top package (Complete), this is only possible via our support team, please call 0333 200 7273