Change the method of curve fitting in fitoptions

I am trying to fit a custom model to some data, and have tried to change the fitoptions of this model:

Off_Fit=fittype('a*exp(b*(x-x0))+c*exp(d*(x-x0))+y0','coefficients',{'a','b'...
                       'c','d','y0'},'problem',{'x0'},'independent','x');
 Op=fitoptions(Off_Fit);                    
 L=[...];  %Lower bounds
 Op.Lower=L;
Op.Method='NearestInterpolant';

All changes except Op.Method are accepted by Matlab; when I try to use the line Op.Method=... above, I get the error

     Changing the 'Method' property of curvefit.basefitoptions is not allowed.
     Error in myScript (line 163)
     Op.Method='NearestInterpolant';

Can someone tell me how I can change the fitting method? I was using https://www.mathworks.com/help/curvefit/fitoptions.html#namevaluepairarguments as a guide. Thanks!

Answer 1

[Matt J]

 Options=fitoptions(Options, 'Method','NearestInterpolant');