To enter a return or expire you must start an activity. To start an activity tap on the paper and pen icon in the middle of the screen.
Now, select the customer you would like to create a return or expired return for.
On the screen, you must select INVOICE.
Select the product you would like to return.
Now, add the QTY you need to return. You will see both Return and Expired return fields at the bottom as shown below.