arduino fuse

How arduino uno the change fuse setting ? Where can I change settings?

if your kit works .. dont 'repair' it

You need an AVR programmer to program the fuses.
It connects to the ICSP header and uses the fuse settings in boards.txt.
Easy way is just to reburn the bootloader.
I use Atmel AVR ISP MKii

Other use a 2nd Arduino with a bootloading sketch. I think this one is the best: