Question

F=kma goes the equation then why is K(constant) always 1 though it can be any number?

Answer 1

I dont know any equation that is F = kma.
I only know F = ma and i know F = kx

Answer 2

mate these are constants of proportionality. you CHOOSE their values according to the units you have chosen. for the netwon's equation, we decided as convention in our units that a Force of 1 Newton is responsible to for 1 m/s^2 acceleration of a body of mass 1Kg.
Hence, we chose our units of the physical quantities involved conveniently such that the constant of proportionality becomes 1.