On the main POS screen, choose the top left menu (3bars) to open the side menu.
Choose Configuration 
Once you are in this menu, choose the Hardware tab at the top of the screen.

Setting Primary Receipt
On the side menu, choose Receipt and verify that you have E500 selected as shown here.


Setting Secondary Receipt
If a 2nd receipt is needed for kitchen tickets, selecting Primary Receipt Printer will route these tickets to the main printer. If a 2nd receipt printer is available via network, select Network and enter the IP address of the 2nd printer.
With Hardware still selected from the top menu, choose Devices from the side menu.
Ensure E500 is selected
With Hardware still selected from the top menu, choose Devices from the side menu.

Ensure E500 is selected and USB.