The transaction owner is the role of the user who created the transaction. To change the owner, from your transaction select Users & contacts > User profile > Transaction owner.
How transaction owner reflects in reports:
The transaction owner is used as a filter in transaction reports. When you filter a report by agent or owner, the transactions surfaced are those where the selected user is set as the transaction owner. Changing the transaction owner reassigns the transaction to a different user for reporting and ownership purposes; it does not change the agents on the transaction or the commission split.
For a video walkthrough of these concepts, watch the tutorial below: