Can’t identify this Breath of the Wild ability

There's no in game option to change it.

American version

• Temperature is Fahrenheit
• AM/PM Clock 12:00 - 11:59 am/pm

European version

• Temperature is Celsius
• 24 Hour Clock 0:00 to 23:59

some stupid workaround:

Use an account tied to a different region, or change the consoles region.

EDIT :

It seems you have a hardcopy version of the game which mean there is nothing you can do except buying EU version of the game.

Easier Way :

(°F - 32) x 5/9 = °C

That's the intended way to use flint. I believe you must hit it with a metal weapon for it to generate a spark to light wood.