2021-2023 F-150: When should I use 4A, 4H, or 4L on snowy roads?

This is my first winter with a truck that has 2H, 4A, 4H, and 4L settings on the 4WD dial. Can I just leave it in 4A all winter, or should I switch to 4H once the roads are fully snow-covered? Also, is it harmful to stay in 4H when the road changes from snow to dry pavement for a few miles?