Simple answer: the Stock Transactions layouts in the Inventory Starter Solution are List View. If you change the layout you are using to Form View you will see only one record at a time.
Less simple answer: since you are obviously beginning to modify the SS, you might prefer to create a new layout for yourself which you particularise to your needs. You could start by duplicating the one you are using and play around with that. That way, you leave the built in layout unchanged in case you still need it.