After installing the printer driver, please go to the Devices and Printers page in the computer settings as shown in the figure, and find the printer device (241-BT) you set up on the page.
Click Printing Preferences - Page Setup - Settings - Paper Name - you can create or edit the size you want.

Tip: It is recommended that the custom size should be consistent with the paper size you actually use.
If the paper you use is the 4*6 white square label paper that comes with the shipping label printer. You need to select the paper type of Gap Paper and the paper size of 101.6×152.4mm (4×6inch).
If you are interested in the operation video, you can click to view the operation video below:
2. Mac
After downloading and installing the printer driver on your Mac, please open system settings in the upper left corner.
Then click Printer & Scanner. You can see that the printer has been added.
You can open a label file on the desktop, and the print settings page will pop up. After selecting the printer, you can adjust and customize the Paper Size.

Tip: It is recommended that the custom size should be consistent with the paper size you actually use.
If the paper you use is the 4*6 white square label paper that comes with the shipping label printer. You need to select the paper type of Gap Paper and the paper size of 101.6×152.4mm (4×6inch).
You can click to view the operation video below:
If you still have questions: