We investigate the Rashba and Dressehaus spin-orbit(SO)couplings in an ordinary GaAs/AlGaAs asymmetric double well,which favors the electron occupancy of three subbands v = 1,2,3.Resorting to an external gate,which adjusts the electron occupancy and the well symmetry,we demonstrate distinct three-level SO control of both Rashba(αv)and Dresselhaus(βv)intraband terms.Remarkably,as the gate varies,the first-subband SO parameters αl and β1 comply with the usual linear behavior,while α2(β2)and α3(β3)respectively for the second and third subbands interchange the values,triggered by a gate controlled band swapping.This provides a pathway towards fascinating selective SO control in spintronic applications.Moreover,we observe that the interband Rashba(ημv)and Dresselhaus(Γμv)terms also exhibit contrasting gate dependence.Our results should stimulate experiments probing SO couplings in multi-subband wells and adopting relevant SO features in future spintronic devices.