Is there any way to change the shipping label setting to the format 4x6?

I read through a lot of this thread and didn’t find the same exact problem I’m having. I get the link to change the print format, I click it, change to 6x4 Thermal, and then click Save. The screen goes back and the page size is still 8.5x11. The save doesn’t work. How can I get it to change to 4x6?