After a flush the bowl fill to 3 3/4 " level. After about 15 minutes level in bowl brops to 2". No leaks appear anywhere. This is the second Cadet 3 we have installed in our home this year. First was perfect

Remove and clean the flush valve and the flush valve seat(it is the flap that opens up to allow water to flush the toilet). Once the edges of the valve and the seat are cleaned, possibly with "0000" grit bulldog steel wool, it should not leak anymore. To make sure it is not leaking, once tank has refilled completely, put some food die in the tank. If, after 10-15 minutes, the water in the toilet bowl is colored, you have a leak from the flush valve. Replacing the flush valve is very easy - just bring the old one with you to the hardware/plumbing store and ask for a replacement. Blessings and good luck!!

Sorry for problem with new toilet.
You say water is leaking out of the bowl?

Toilets have 2 parts:
1) Tank: where water is stored for the flush and is sealed with a flapper.
2) Bowl: where water flushes down.

a) If tank is leaking water, then flapper is suspect. Replace flapper and see if that works.
Lift up flapper and run finger around rim to see if there is a rough spot that would indicate flush valve is defective, and needs replacement.
See typical flush valve

b) If bowl is leaking, that is very unusual and would indicate a crack in the porcelain.

If installer sold you the toilet, it is his responsibility to make good on product.
All products are guarantee against workmanship flaws.

As long as the water in the bowl dosent go below the bottom rim your ok there is a trap that the water has to seal that all it needs look at the side of your toilet you will see the trap water saver

theres probably debrie in flush valve, mite also try putting food dye in tank (any color) if it appears in bowl the flapper is seeping water and activating flush valve..

Check to be sure small tube is flowing inside the ovefow tube. This is the water that flushes the rim holes, and refills the bowl. If you don't have flow clean or replace the float valve.

try putting some food coloring in it to see if it's leaking anywhere. the coloring will help you identify where it's leaking

First, fyi, adjusting the knob? in the tank, or the fill level will not increase the amount of water in the bowl. The bowl fills to a certain point, and then as more water is added it starts to go over the built in trap, and down the drain. When you flush the toilet, all the water in the tank dumps into the bowl, and the existing water is pushed over the trap and down the drain. All of this being said it sounds like you may either have an internal crack, between the bowl and trap; you may have a crack that is draining under your toilet, (water spots?), or you have a more serious plumbing issue, improper venting, which is causing a vacuum, and pulling the water out. Hope this helps.

If very little water is used on initial flush, The bowl is functioning as a tank for second thorough flush. The high water level cannot stay high in the bowl while in motion or you would have a mess ion start and stops.

The tank holding the proper amount of water is a good sign. The inside of the stool is like the GOOSE NECK under you sink. It always holds water. This may sound like a bit of a hassle to do but if all 3 toilets are identical, here is what you can try if you are a bit handy. Go to the hardware store and purchase 4 toilet wax rings with a plastic flange and a few sets of toilet floor flange bolts(they are cheap and you can always return if not used, as It is better to have xtra parts on hand). Turn off the water supply to the "Mystery Toilet". Leave the tank and everything connected to the stool. Flush the toilet and remove all excess water from the tank and bowl. This can be done with a shop vac, sponge or towel. Disconnect the water supply to the tank. Remove the bolts holding the stool to the floor and carefully remove toilet. Scrap off all the old wax from the floor flange and bottom of stool. Now go and repeat this proceedure to one of the toilets that is working properly. In other words Switch the "Mystery Toilet" with a "Working Toilet" and see how they react. If the working toilet does it in the same bathroom and the "Mystery Toilet" does not do it in the other bathroom then you probably have a VENTING PROBLEM. If the "Mysery Toilet" Does it in the other bathroom then you most likely have a Defective Toilet. This Job is best done by 2 people, as it can sometimes be challenging to center the new wax ring on the toilet flange. Reconnect to the floor and reconnect water supply to the tanks. DO NOT OVERTIGHTEN BOLTS to the floor flange as you may crack the toilet. All drain lines must be vented properly for water to flow. If you are curious check out drain venting on the internet. Also, sometimes a vent can become obstructed with debris, ice, bird nest, etc.. I would 1st check the vent on the roof visually and then have someone flush and listen. If you believe the vent is clear....Then do the toilet switch and go from there.....Hope this helps and Happy Holidays....Joe