Who determines the title of an initiative?

Constitution (2017)

Section 133.  A bill shall be first submitted to the House of Representatives and may be introduced only by the followings:

(1) Council of Ministers;

(2) Members of the House of Representatives of not fewer than twenty in number;

(3) persons having the right to vote of not less than ten thousand in number who submit a petition to introduce a bill under Chapter III Rights and Liberties of the Thai People  or  Chapter V Duties of  the  State and  in  accordance  with  the  law  on the  public submission of a bill.

If  a  bill  introduced  by  persons under  (2)  or  (3)  is  a  money  bill,  it may be introduced only with the endorsement of the Prime Minister.