Owner Teams and Viewing Opportunities

We have UserX who is part of an owner team associated with an account. The UserX and the Owner Team both have the SalesPerson Role (see role security below). There are several other users also associated with this owner team. 

When a new opportunity is created for the account by any of the other team members, UserX can see and edit those opportunities. We need for those opportunities created by other members of the owner team to only be visible by the person who created the opportunity.

I understand that I can create a view which excludes the other users opportunities. Managers have rights to the business unit and it is okay for them to see all activities, but the individual team members should only be able to see their own opportunities. If I remove UserX from the owner team associated with the account, they can no longer view or edit the other team members opportunities associated with this account.

Any advice would be appreciated, thank you.