There are two ways to reimburse an expense transaction. You can either make the expense transaction billable and add it to an invoice, or create a journal entry.
If you want to reimburse it through an invoice, here's how to turn on the billable function:
1. Click the Gear icon in the upper-right corner, and select Account and Settings.
2. Select the Expenses tab and go to the Bills and expenses section.
3. Turn on the Make expenses and items billable function.