Water heater flame help - adjustments not having any effect

That air/mixture window needs to be fully open and any restrictions removed for more air to move toward a blue flame.
I would also consider adjusting the propane valve to reduce the flame to see if it helps. Note the position of the adjusting screw to put it back same if no help.
Soot in the combustion chamber can also affect how it burns. Give it a light scraping or brushing then sweep it out.