Users with admin-level permissions can assign expenses, or any other transactions, to a specific label for better tracking.
Click the Accounts button if necessary, and then select the transaction from the Dashboard or Account page. (For more information about transactions, see Transaction Tables.)
Click the Add Label button in the Rho Attributes section of the transaction details section. Then select the desired label(s) and click Apply.

The expense is now assigned to that label. For more information about labels, see How do I create a new label?