When you load in a new direct thermal label, there are two actions that need to take place:

1) Run the automatic label identification on the printer.

2) Set proper label settings on your computer. 

1)Run the automatic label identification.

①Disconnect the USB cable from your printer, then turn the printer off. Press and hold the Feed Button while turn the power ON, until you see the purple light flashing one time, then release.   

②Printer will determine the gap size and other properties of your label. 

③After the determine, re-connect the USB cable to the printer and resume printing.

Check the video "Automatic label identification"