I do not understand how how my qualified business income was calculated for my deduction , It doesn't seen to be my net or gross income , please help .

I had the same problem.  I have self -employed health insurance for the business.  On the smart worksheet for Schedule C "Qualified Business Income Deduction Info"  this amount, plus the deduction for 1/2 the self employment tax are both deducted from my net business income to arrive at the Qualified amount.  Apparently, even though these amounts are adjustments to income on my form 1040, they are considered a reduction of net income from my business for this calculation.