Change default tolerance on Flood Fill Tool

[dmmobley]

I am using AF to preprocess 100 year old company publications prior to OCRing them. The pages are very yellowed and I find the flood fill tool a good way to change the background yellow to white. However, I am constantly changing the 20% default tolerance on the flood fill tool to 7%. When I change to a different image, it reverts to the 20% again. I can't seem to find a way to change the default to make it stick. Could this be made an item in Preferences or be made a sticky value that goes across images?