There needs to be an air gap between the fill tube and the top of the overflow.
The water level in the tank should be about 1/2" down from the top of the overflow.
Make sure the flapper is sealing.
My Kohler Ingenium 85297-AA toilet was continually running water from the feeder tube causing the water in the tank to overflow into the center tube. I tried adjusting the clips to move the fill valve lower. At some point while making this adjustment, the fill valve assembly raised up causing the feeder tube to become unclipped from the center tube. I pushed white section of the fill valve assembly down low enough to allow the cover to be replaced and then adjusted the clips again. This solved the problem of the water overflowing into the center tube, but caused a different problem. Now the toilet flush is weak and does not create enough force to remove waste. When the toilet is flushed the water is not removed from the bowl, but rather the water level in the bowl increases. After the tank refills, the water level in the bowl is very high and I can hear water moving down through the pipes for about a minute after the flush is completed. Can anyone help??
My experience with the Ingenium flush is that there is usually no difference between how a clogged and unclogged toilet flush. Maybe a little.
Seriously consider replacing the thing with something that works well.