The Staff field identifies whose work or cost the entry represents.
Without Edit Expenses or Approve Expenses permission, the form limits the staff selection to yourself. Add Time Entries or Add Expenses is still needed for the corresponding type of new line. Permission to enter another person's work does not automatically grant access to every case.
Use Edit on an eligible entry and correct Staff, then Save Changes. Approved, paid, invoiced, or payment-slip-linked entries can require additional correction steps before editing is allowed. Changing the staff member can affect who is paid, so verify the applicable rate and do not simply create a duplicate under the correct person.
The controls you see depend on your permissions, access to the case, the case status, and the entry's review, invoice, and payment state. If an action is missing, ask your CaseWyze administrator to check these conditions.