The fuses are only set when you do a Tools > Burn Bootloader, for which you need to connect an ISP programmer to your Nano. The fuses are not set when you do a regular upload to your Nano.
The fuses are only set when you do a Tools > Burn Bootloader, for which you need to connect an ISP programmer to your Nano. The fuses are not set when you do a regular upload to your Nano.