I used to be a young Earther. The more I studied it from a scientific standpoint (and theological) the whole thing came crashing down around me like a house of cards.
The best scientific explanation I heard was one that compared the measurements taken of the speed of light throughout time. Galileo (I think?) used Jupiter’s moons to calculate it and got a much faster speed than we know it to be now. A few hundred years later another method was used and it was slower, but still faster than it is now. The Young Earthers I read this from propose that at the creation of the Universe the speed of light was much, much, MUCH faster than it is now, and has been exponentially slowing down. So, light that would appear to be millions or even BILLIONS of years old, would only appear to be that old because the light was originally travelling much faster.
Obviously I feel this explanation has a lot of holes in it, not the least of which is the accuracy of measurements taken by telescope hundreds of years ago…but this was the most scientifically minded explanation I heard.