How can I repair this gas leak on my new range? Teflon tape isn't working
Stop, turn off the gas, ventilate the house, and hire a pro.

If you applied teflon tape to a flare fitting, you are NOT the person to be installing your gas range. You fundamentally don't understand what you are doing, and doing this wrong can blow up your house. That tends to impair the "learn from your mistakes" method of learning. This is not the place to be "figuring it out as you do it the first time."

Removing the teflon tape from the flares won't magically make you competent to safely complete the job correctly, so my advice is let a pro who knows what they are doing do it.