How can I learn to properly adjust the air to burner ratio to stop my sister's furnace from making a loud pop, due to the gas filling up, yet the pilot not lighting right away

How can I properly adjust my sister's air to burner ratio, using the slots to adjust the air so that the furnace does not make a loud pop/bang, due to the furnace burner area filling with gas and the pilot not lighting it right away

Something like this is best left to a pro with combustion test equipment. Improper air adjustment can be extremely dangerous, even deadly.