Yorkshire Bike Shop has a liberal return policy

Yorkshire Bike Shop has a liberal return policy. A customer can return

any product for a full refund within 14 days of purchase. When a customer returns merchandise, Yorkshire policy specifies the following:

-Store clerk issues a prenumbered return slip, refunds cash from the cash register, and keeps a copy of the return slip for review by the manager.
-Store clerk places the returned goods back on the shelf or on the floor as soon as possible.Yorkshire uses a periodic inventory system.
Required

-How can a dishonest store clerk steal from Yorkshire? What part of company policy enables the store clerk to steal without getting caught?
-How can Yorkshire improve its internal controls to prevent this theft?