Seat too low and too far back causes much higher knee pains than too high or too far forward. Actually there's zero knee pain with too high & too far forward, it's really stretching the tendons & ligaments behind your knee.

Also too low a seat uses primarily the quads to drive the pedals and you end up overloading them. Having a higher seat allows you to recruit the hamstrings and glutes into the pedal stroke. You go a lot faster for the same effort.

Basic test of seat-height is to put your heels on the pedal and spin backwards. At the bottom of the pedal-stroke, you should have full leg extension. This is the lowest the seat should be and a lot of people have it 1/4 to1/2" higher depending upon the pedal-type and cleat-thickness.