Open the system folders.

CLICK on "config.g" file to open and edit.

Don't be concerned if your config.g file looks a little different from the picture. Don't change your file. Just add to it.

Add the new lines below comments for the hotend fan. The new lines are shown in the photo and below, then save

M591 D0 P2 C3

M581 E0:1 S0 T2 C0

Power cycle your printer.