How can I set the percentage of auto-reduction in the auto-reduction function, for example, I want to reduce by 1% in each step until I find buyers?

There are a number of parameters in the strategy settings, which are responsible for auto-reduction of a Sell order after a certain period of time. The parameter that you need is PriceDownPercent, which contains a number in percentage terms of how much to reduce the price of the sell order at each step of the auto-reduction. In your case you should set it like this: PriceDownPercent=1.