Oomis, I strongly suspect that you may have misinterpreted what you heard. Are you positive that you received a psak allowing you to adjust a flame up and down at will?
ABSOLUTELY sure. My grandfathers on both sides of the family were rabbonim and both my bubbies and all my aunts, as well as my mom ALL turned the oven on and off on yom tov. So did my rebbetzin (whose husband Z”TL was a close personal chaver of R’ Moshe Z”TL, and whom R’ Moshe would often call for his own personal shailos). If you are younger than your fifties, then you might not remember the type of oven I am talking about. The halacha is very specific. You may not create a new spark of fire, but if the fire is already there and not going out, you may move it from one place to another. hence you may turn the burner up or down, because the flame is just going back to its first location (the pilot, which btw is STILL burning even when the burner is turned on), or moving from that location to the burner holes. I am flabbergasted that anyone could be unfamiliar with this, but the truth is today’s ovens cannot likewise be used. I will tell you something more – way more radical, though I personally do NOT do this, and most frum Jews today would not do this. There was a time around 50-60 years ago or so, that people turned their electricity on and off on yom tov, as well. The sevara at the time was that like the fire in the pilot light, the electricity (also called aish) is contantly running through the switches and cords. Proof of that is that if you would stick a metal object in an outlet, or cut open a wire that is plugged into a live outlet and touch the wire, you would be electrocuted, chalilah. Those that held it was permissible, held that for tzorech yom tov it was like turning the burners on and off with a continuous pilot. Most of us do not hold by that today, but there are many frum people who hold that a light may be turned on, but not off. We do not so either of those things, we use timers for our electric needs for lamps and fans. Incidentally, the halacha is that if you know a Yid who DOES turn lights on and off on yom tov, you may NOT castigate him for doing so, based on the previously held belief (which btw, I saw this entire discussion in the JEwish Press several years ago). Check with your LOR.
I have asked this particular question throughout my life, as different inyanim came up, and without exception every teacher, every rov, has always said that it is permitted to turn a burner on and off on the specific type of stove that we have. It is absolutely not permitted to do so if I would have to light the pilot first. Very straightforward, not subject to misinterpretation.