OK I have an actual answer for you. I think people are giving you a hard time because you worded your inquiry/title oddly. You wrote, "How do I stop flooring it on yellows?" The obvious answer is, "Don't always floor it when the light turns yellow."

What you meant was, "How do I know whether or not I should increase speed, stay the same speed, or brake when the light turns yellow?"

Honestly, to be safe I would first stick with either staying the same speed or braking. When the light turns yellow, you have to consider the following immediately:

1. your current speed
2. your distance from the light
3. whether you are currently accelerating, keeping a constant speed, or decelerating

You have to make the decision immediately when the light turns yellow. If you take too long to decide to brake, the brake is sudden and dangerous.

As a super rough example, if you're going 40mph and the light turns yellow when you're 30ft away, you should keep that speed because you're close enough that the light won't turn yellow before your cross the intersection.

If you're going 40mph and you're 120ft away, you're not going to make it across the intersection before the light turns red at that speed. The yellow lights are timed such that if you begin braking soon after the light turns yellow, your stop will be smooth and safe (not sudden, which could theoretically lead to you getting rear ended).

Stick to just those two options for now so that you get an idea of how far you should be and at what speeds in order to brake safely or roll through safely.

There may be situations when it is in your best interest to increase throttle at a yellow, but DO NOT go wide open throttle every time you hit a yellow and there's no one in front of you. You can't beat every yellow light. It is literally impossible. For example, if you're 250ft from the light and it turns yellow and you're going 40mph, you may feel the impulse to floor it since there's no one in front of you. This is incredibly dangerous because if you don't make it and it turns red before you cross you might t-bone a car crawling through the intersection while you are flying through at 70mph. You could literally kill the driver.