I don't know of anyway to change the time the igniter is on, I believe it is timed from the board and shuts down.
No OAK. Then you are using the air in the house only. If your house is tightly insulated, if you have a different exhaust fan running in the bathroom or kitchen that may cause the stove to starve for air. It doesn't matter how much space you have behind or around the stove, you will be adjusting the draft from the manual draft directly under the burn pot.
Previous post you said that you were pulling the damper out about 3/4"-1". I have OAK and the only time I use the manual damper is when starting the stove and I pull mine out at least 1 1/4". You will need to pull yours out further and watch what the pellets do. If they start to build up without burning good then pull the damper out a little more, 1/4" at a time. If it looks like they are burning good but the feed rate isn't keeping up push it in a 1/4" inch at a time. You should have a nice lively fire, don't worry about how high the flames are just that it's burning nice without overfilling or underfeeding and going out in either case.
Here's where the draft setting and the feed rate blend to get the stove running right. First you post that on HR1 it shows 1pph, is that correct? If so you need to bump that number up to 2pph, 1pph is way to low to get the stove up to temp to run properly unless they have some new super btu pellet that I haven't seen yet.
To change the HR1 ( guess it Pr1 or Cr1 on the new board) push the HR1 down button and the AUX down button at the same time, when the board changes state and show the feed rate then push the AUX up button until it shows 2pph, if you go past just push the AUX down button to get it where you want. When you get it where you want push the ON button to make the new setting take affect.
Your DF settings are good to start with, don't mess with those considering you are using the manual draft, those are the factory defaults.
It can take some time to adjust these stoves but it can be done and once you learn it it will come easier each time. The only other thing I can think of is if the jumper on the board for the t-stat is missing, that would cause the board to only feed on the lowest setting even if you bump it up on the board. If all else fails and you pull off the side panel where the board is you can see if the jumper is in place, if not then you need to get one or jump it temporarily with a thin wire. I'll try and post a pic I found on another thread of the board pointing out the jumper.
View attachment 169472
See where the arrow points, just to the right there is a little black jumper on the board, next to the blue connector on the right. That is the jumper. Be VERY careful if you try and handle the board, discharge any static from yourself or the board go be useless!