Hello D. Young,
Thank you for your question on the Delta Prelude Elongated Toilet and I am happy to assist you with this today.
Please visit the link below to see a step by step procedure to make minor and major water level adjustments in the tank (Part Two and Three):
The flapper for this model is designed to only stay open for a half a second when you press the handle down, although if you wish to allow more water in the bowl, you will need to hold the flush lever down for a few seconds so the trip lever will allow the flapper lid to stay open for a few seconds longer.
I hope this information is helpful!
Please feel free to give us a call if we can help with anything further on our warranty line at 855-345-1345.
Delta Faucet Company
Date published: 2017-12-06