MATLAB IIRs -- extracting and scaling the coefficients of second order sections
These scale values are applied before and after each section, so for $N$ sections you have $N+1$ scale values. Check the Matlab documentation, there must be some related property that you can set to 'scalar', and this will give you a single total scaling value. In any case, the total scaling is just the product of the three values in your case. So you have to multiply the b coefficients of one filter section by the product of all scale values, then the total scaling will be OK, i.e. the maximum frequency response magnitude will be 0 dB.