Guest users are limited to accessing a single case in your account at a time. To change which case a guest can access, you must first remove them from the case to which they are currently assigned.
To remove a guest user from a case, click on the white "+" button in the top right corner of the case home page, locate the user in the menu that appears and click the 'x' button to the right user's name.
Once a guest user has been removed from a case, you are then able to assign them to a different case within your account. In the new case, click the white "+" button at the top right. Click "Add more users" and locate the user's existing profile in the list. Click the "+" button next to their name to assign them to the case.
Note: If the message "Upgrade to add" appears next to the guest users' name on the above screen, they are still showing as assigned to a different case on the account. Try refreshing your browser, or visit the Cases list and filter by the user's name to identify the specific case to which they are currently assigned.
For more information about user permissions levels in CaseFleet, click here.